Update backward extremity docs to make it clear that it does not indicate whether we have fetched an events' `prev_events` (#11469)

Spawning from https://github.com/matrix-org/synapse/pull/9445#discussion_r758958181



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

Support configuring the lifetime of non-refreshable access tokens separately to refreshable access tokens. (#11445)

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

by calling into `make_test_homeserver_synchronous`.

The function *could* have been inlined at this point but the function is big enough

and it felt fine to leave it as is.

At least there isn't a confusing name clash anymore!

It had no users.

We have just taken the identity of a previous function but don't provide the same
behaviour, so we need to fix this in the next commit...

and pass in the homeserver rather than calling a same-named function to ask for one.

Later commits will jiggle things around to make this sensible.

We're going to add a `state_key` column to the `events` table, so we need to
add some disambiguation to queries which use it.

This mainly consists of docstrings and inline comments. There are one or two type annotations and variable renames thrown in while I was here.

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

* move wiki pages to synapse/docs and add a few titles where necessary

* update SUMMARY.md with added pages

* add changelog

* move incorrectly located newsfragment

* update changelog number

* snake case added files and update summary.md accordingly

* update issue/pr links

* update relative links to docs

* update changelog to indicate that we moved wiki pages to the docs and state reasoning

* requested changes to admin_faq.md

* requested changes to database_maintenance_tools.md

* requested changes to understanding_synapse_through_graphana_graphs.md

* add changelog

* fix leftover merge errata

* fix unwanted changes from merge

* use two spaces between entries

* outdent code blocks

This skips a few methods which are difficult to type.

Add MSC3030 experimental client and federation API endpoints to get the closest event to a given timestamp (#9445)

MSC3030: https://github.com/matrix-org/matrix-doc/pull/3030



Client API endpoint. This will also go and fetch from the federation API endpoint if unable to find an event locally or we found an extremity with possibly a closer event we don't know about.
```
GET /_matrix/client/unstable/org.matrix.msc3030/rooms/<roomID>/timestamp_to_event?ts=<timestamp>&dir=<direction>
{
    "event_id": ...
    "origin_server_ts": ...
}
```

Federation API endpoint:
```
GET /_matrix/federation/unstable/org.matrix.msc3030/timestamp_to_event/<roomID>?ts=<timestamp>&dir=<direction>
{
    "event_id": ...
    "origin_server_ts": ...
}
```

Co-authored-by: Erik Johnston <erik@matrix.org>

* move wiki pages to synapse/docs and add a few titles where necessary

* update SUMMARY.md with added pages

* add changelog

* move incorrectly located newsfragment

* update changelog number

* snake case added files and update summary.md accordingly

* update issue/pr links

* update relative links to docs

* update changelog to indicate that we moved wiki pages to the docs and state reasoning

* revert unintentional change to CHANGES.md

* add link

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

* Update CHANGES.md

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

This adds some misc. type hints to helper methods used
in the `synapse.config` module.

As specified for Matrix v1.1.

fix header level

Dex isn't yet [1,2] a certified OpenID Provider implementation. As of today, it's not on the list maintained by the OpenID Foundation. [3]

[1] https://github.com/dexidp/dex/issues/42
[2] https://github.com/dexidp/dex/issues/262
[3] https://openid.net/certification/

* Add note to postgres doc about hugepages

* Newsfragment

* Add check to catch syanpse master process starting when workers are configured

* add test to verify that starting master process with worker config raises error

* newsfragment

* specify config.worker.worker_app in check

* update test

* report specific config option that triggered the error

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

* clarify error message

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

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

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

Per updates to MSC2675 which now states that bundled
aggregations should be included from the `/relations`
endpoint.

When all entries in an `LruCache` have a size of 0 according to the
provided `size_callback`, and `drop_from_cache` is called on a cache
node, the node would be unlinked from the LRU linked list but remain in
the cache dictionary. An assertion would be later be tripped due to the
inconsistency.

Avoid unintentionally calling `__len__` and use a strict `is None`
check instead when unwrapping the weak reference.

The tests helpers automatically convert dictionaries to
JSON payloads, no need to do it manually for each
test.

If you're trying to shut down Synapse, it's rather handy if it *actually* shuts
down before you move on.

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>