Use Pydantic to systematically validate a first batch of endpoints in `synapse.rest.client.account`. (#13188)

Instrument FederationStateIdsServlet - `/state_ids` so it's easier to follow what's going on in Jaeger when viewing a trace.

This reverts commit f383b9b3. Other PRs
were seeing mypy failures that looked to be related to mypy-zope.
Confusingly, we didn't see this on #13521.

Revert this for now and investigate later.

* Clarifies comments.
* Fixes an erroneous comment (about return type) added in #13455
  (ec248132).
* Clarifies the name of a variable.
* Simplifies logic of pulling out the latest join for the requesting user.

Signed-off-by: James Barton <james@neodon.com>

Add note to `redaction_retention_period` documentation mentioning that event purging runs at most every 5m (#13492)

Events can be un-rejected or newly-rejected during resync, so ensure we update
the database and caches when that happens.

Revert 'Remove the unspecced  field in the  response. (#13365)' to give more time for clients to update. (#13501)

* Use literals in place of `HTTPStatus` constants in tests

* newsfile

* code style

* code style

Add some miscellaneous comments to document sync, especially around
`compute_state_delta`.

Signed-off-by: Sean Quah <seanq@matrix.org>

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

```py
@trace
@tag_args
async def get_oldest_event_ids_with_depth_in_room(...)
  ...
```

Before this PR, you would see a warning in the logs and the span was not exported:
```
2022-08-03 19:11:59,383 - synapse.logging.opentracing - 835 - ERROR - GET-0 - @trace may not have wrapped EventFederationWorkerStore.get_oldest_event_ids_with_depth_in_room correctly! The function is not async but returned a coroutine.
```

Replace
- `HTTPStatus.NOT_FOUND`
- `HTTPStatus.FORBIDDEN`
- `HTTPStatus.UNAUTHORIZED`
- `HTTPStatus.CONFLICT`
- `HTTPStatus.CREATED`

Signed-off-by: Dirk Klimpel <dirk@klimpel.org>

In state res v2, we apply two passes of iterative auth checks. The first
pass replays power events and events in their auth chains, but only
those belonging to the full conflicted set. The source code as written
suggests that we want only those belonging to the auth difference (which
is a smaller set of events).

At runtime we were doing the correct thing anyway, because the only
callsite of `_reverse_topological_power_sort` passes in the
`full_conflicted_set`. So this really is just a rename.

This adds support for the stable identifiers of MSC2285 while
continuing to support the unstable identifiers behind the configuration
flag. These will be removed in a future version.

Co-authored-by: MattC <buffless-matt@users.noreply.github.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

Fix @tag_args being off-by-one (ahead)

Example:

```
argspec.args=[
  'self',
  'room_id'
]

args=(
  <synapse.storage.databases.main.DataStore object at 0x10d0b8d00>,
  '!HBehERstyQBxyJDLfR:my.synapse.server'
)
```

---

The previous logic was also flawed and we can end up in a situation like this:

```
argspec.args=['self', 'dest', 'room_id', 'limit', 'extremities']

args=(<synapse.federation.federation_client.FederationClient object at 0x7f1651c18160>, 'hs1', '!jAEHKIubyIfuLOdfpY:hs1')
```

From this source:
```py
async def backfill(
    self, dest: str, room_id: str, limit: int, extremities: Collection[str]
) -> Optional[List[EventBase]]:
```

And this usage:
```py
events = await self._federation_client.backfill(
    dest, room_id, limit=limit, extremities=extremities
)
```

which would previously cause this error:
```
synapse_main | 2022-08-04 06:13:12,051 - synapse.handlers.federation - 424 - ERROR - GET-5 - Failed to backfill from hs1 because tuple index out of range
synapse_main | Traceback (most recent call last):
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/handlers/federation.py", line 392, in try_backfill
synapse_main |     await self._federation_event_handler.backfill(
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/logging/tracing.py", line 828, in _wrapper
synapse_main |     return await func(*args, **kwargs)
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/handlers/federation_event.py", line 593, in backfill
synapse_main |     events = await self._federation_client.backfill(
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/logging/tracing.py", line 828, in _wrapper
synapse_main |     return await func(*args, **kwargs)
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/logging/tracing.py", line 827, in _wrapper
synapse_main |     with wrapping_logic(func, *args, **kwargs):
synapse_main |   File "/usr/local/lib/python3.9/contextlib.py", line 119, in __enter__
synapse_main |     return next(self.gen)
synapse_main |   File "/usr/local/lib/python3.9/site-packages/synapse/logging/tracing.py", line 922, in _wrapping_logic
synapse_main |     set_attribute("ARG_" + arg, str(args[i + 1]))  # type: ignore[index]
synapse_main | IndexError: tuple index out of range
```

* Adds docstrings and inline comments.
* Formats SQL queries using triple quoted strings.
* Minor formatting changes.
* Avoid fetching `event_push_summary_stream_ordering` multiple times
  in the same transactions.

Faster Room Joins: prevent Synapse from answering federated join requests for a room which it has not fully joined yet. (#13416)

Still maintains local in memory lookup optimisation, but does any external
lookup as part of the deferred that prevents duplicate lookups for the same
event at once. This makes the assumption that fetching from an external
cache is a non-zero load operation.

Fixes: #12534

Signed-off-by: Dirk Klimpel <dirk@klimpel.org>