Remove legacy code related to deprecated `trust_identity_server_for_password_resets` config flag (#11333)

* remove code legacy code related to deprecated config flag "trust_identity_server_for_password_resets" from synapse/config/emailconfig.py

* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/config/registration.py

* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/handlers/identity.py

* add tests to ensure config error is thrown and synapse refuses to start when depreciated config flag is found

* add changelog

* slightly change behavior to only check for deprecated flag if set to 'true'

* Update changelog.d/11333.misc

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

Adds validation to the Client-Server API to ensure that
the potential thread head does not relate to another event
already. This results in not allowing a thread to "fork" into
other threads.

If the target event is unknown for some reason (maybe it isn't
visible to your homeserver), but is the target of other events
it is assumed that the thread can be created from it. Otherwise,
it is rejected as an unknown event.

Otherwise I get this beautiful stacktrace:

```
python3 -m synapse.app.homeserver --config-path /etc/matrix/homeserver.yaml
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/root/synapse/synapse/app/homeserver.py", line 455, in <module>
    main()
  File "/root/synapse/synapse/app/homeserver.py", line 445, in main
    hs = setup(sys.argv[1:])
  File "/root/synapse/synapse/app/homeserver.py", line 345, in setup
    config = HomeServerConfig.load_or_generate_config(
  File "/root/synapse/synapse/config/_base.py", line 671, in load_or_generate_config
    config_dict = read_config_files(config_files)
  File "/root/synapse/synapse/config/_base.py", line 717, in read_config_files
    yaml_config = yaml.safe_load(file_stream)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/__init__.py", line 125, in safe_load
    return load(stream, SafeLoader)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/__init__.py", line 81, in load
    return loader.get_single_data()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/constructor.py", line 49, in get_single_data
    node = self.get_single_node()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 82, in compose_node
    node = self.compose_sequence_node(anchor)
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/composer.py", line 110, in compose_sequence_node
    while not self.check_event(SequenceEndEvent):
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/parser.py", line 379, in parse_block_sequence_first_entry
    return self.parse_block_sequence_entry()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/parser.py", line 384, in parse_block_sequence_entry
    if not self.check_token(BlockEntryToken, BlockEndToken):
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/scanner.py", line 227, in fetch_more_tokens
    return self.fetch_alias()
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/scanner.py", line 610, in fetch_alias
    self.tokens.append(self.scan_anchor(AliasToken))
  File "/root/synapse/env/lib/python3.8/site-packages/yaml/scanner.py", line 922, in scan_anchor
    raise ScannerError("while scanning an %s" % name, start_mark,
yaml.scanner.ScannerError: while scanning an alias
  in "/etc/matrix/homeserver.yaml", line 614, column 5
expected alphabetic or numeric character, but found '.'
  in "/etc/matrix/homeserver.yaml", line 614, column 6
```

Signed-off-by: Nicolai Søborg <git@xn--sb-lka.org>

* Add support for `/_matrix/media/v3` APIs

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Update `workers.md` to use v3 client and media APIs

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Add changelog

Signed-off-by: Aaron Raimist <aaron@raim.ist>

By reverting changes from #11166 in this script. Specifically commit
13f084eb.

Synapse 1.47.0rc3 (2021-11-16)
==============================

Bugfixes
--------

- Fix a bug introduced in 1.47.0rc1 which caused worker processes to not halt startup in the presence of outstanding database migrations. ([\#11346](https://github.com/matrix-org/synapse/issues/11346))
- Fix a bug introduced in 1.47.0rc1 which prevented the 'remove deleted devices from `device_inbox` column' background process from running when updating from a recent Synapse version. ([\#11303](https://github.com/matrix-org/synapse/issues/11303), [\#11353](https://github.com/matrix-org/synapse/issues/11353))

Different users may be allowed to see different rooms within a space,
so sharing responses between users is inadvisable.

This is one of the changes required to support Matrix 1.1

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

Signed-off-by: Ashwin S. Nair <58840757+Ashwin-exe@users.noreply.github.com>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

It already seems to pass mypy. I wonder what changed, given that it was
on the exclusion list. So this commit consists of me ensuring
`--disallow-untyped-defs` passes and a minor fixup to a function that
returned either `True` or `None`.

* Add support for the stable version of MSC2778

Signed-off-by: Tulir Asokan <tulir@maunium.net>

* Expect m.login.application_service in login and password provider tests

Signed-off-by: Tulir Asokan <tulir@maunium.net>

* remove unused tables room_stats_historical and user_stats_historical

* update changelog number

* Bump schema compat version comment

* make linter happy

* Update comment to give more info

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

I was sad that I couldn't do better for
`_curr_state_delta_stream_cache`. At least it's explicitly called out in
a comment with #TODO.

This was only checking the __init__ files in modules instead of
all files in a module, which don't pass yet.

* Prefer `HTTPStatus` over plain `int`

This is an Opinion that no-one has seemed to object to yet.

* `--disallow-untyped-defs` for `tests.rest.client.test_directory`
* Improve synapse's annotations for deleting aliases
* Test case for deleting a room alias
* Changelog

* change display names/avatar URLS to None if they contain null bytes

* add changelog

* add POC test, requested changes

* add a saner test and remove old one

* update test to verify that display name has been changed to None

* make test less fragile

* Make DataStore inherit from EventForwardExtremitiesStore before CacheInvalidationWorkerStore

the former implicitly inherits from the latter, so they should be
ordered like this when used.

* Annotate HomeserverTestCase.servlets
* Correct annotation of federation_auth_origin
* Use AnyStr custom_headers instead of a Union

This allows (str, str) and (bytes, bytes).
This disallows (str, bytes) and (bytes, str)

* DomainSpecificString.SIGIL is a ClassVar