`defer.returnValue` was only needed in Python 2; in Python 3, a simple
`return` is fine.

`twisted.internet.defer.returnValue` is deprecated as of Twisted 24.7.0.

Most uses of `returnValue` in synapse were removed a while back; this
cleans up some remaining bits.

I thought ruff check would also format, but it doesn't.

This runs ruff format in CI and dev scripts. The first commit is just a
run of `ruff format .` in the root directory.

During the migration the automated script to update the copyright
headers accidentally got rid of some of the existing copyright lines.
Reinstate them.

Part of #9366

Adds in fixes for B006 and B008, both relating to mutable parameter lint errors.

Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

Run `isort`, `flake8` and `black` over the `contrib/` directory and `synctl` script. The latter was already being done in CI, but now the linting script does it too.

Fixes https://github.com/matrix-org/synapse/issues/7910

Allow Synapse to send registration emails + choose Synapse or an external server to handle 3pid validation (#5987)

This is a combination of a few different PRs, finally all being merged into `develop`:

* #5875 
* #5876 
* #5868 (This one added the `/versions` flag but the flag itself was actually [backed out](https://github.com/matrix-org/synapse/commit/891afb57cbdf9867f2848341b29c75d6f35eef5a#diff-e591d42d30690ffb79f63bb726200891) in #5969. What's left is just giving /versions access to the config file, which could be useful in the future)
* #5835 
* #5969 
* #5940

Clients should not actually use the new registration functionality until https://github.com/matrix-org/synapse/pull/5972 is merged.

UPGRADE.rst, changelog entries and config file changes should all be reviewed closely before this PR is merged.

* Fix seven contrib files with Python syntax errors

Signed-off-by: cclauss <cclauss@me.com>

Functions from syutil.crypto.jsonsign are now available in
signedjson, so use that instead of depending on syutil.

Signed-off-by: Andrew Shadura <andrew@shadura.me>

fix the copyright holder from matrix.org to OpenMarket Ltd, as matrix.org hasn't been incorporated in time for launch.

change the world: make the default matrix API URL prefix /_matrix rather than /matrix to make it easier for existing websites to mount a HS in their namespace without collisions.

perl -pi -e 's#/matrix#/_matrix#g' ./cmdclient/console.py ./docs/client-server/howto.rst ./docs/client-server/specification.rst ./docs/client-server/swagger_matrix/directory ./docs/client-server/swagger_matrix/events ./docs/client-server/swagger_matrix/login ./docs/client-server/swagger_matrix/presence ./docs/client-server/swagger_matrix/profile ./docs/client-server/swagger_matrix/registration ./docs/client-server/swagger_matrix/rooms ./docs/server-server/specification.rst ./graph/graph.py ./jsfiddles/create_room_send_msg/demo.js ./jsfiddles/event_stream/demo.js ./jsfiddles/example_app/demo.js ./jsfiddles/register_login/demo.js ./jsfiddles/room_memberships/demo.js ./synapse/api/urls.py ./tests/federation/test_federation.py ./tests/handlers/test_presence.py ./tests/handlers/test_typing.py ./tests/rest/test_events.py ./tests/rest/test_presence.py ./tests/rest/test_profile.py ./tests/rest/test_rooms.py ./webclient/components/fileUpload/file-upload-service.js ./webclient/components/matrix/matrix-service.js

Support multiple login flows when deciding how to login. Updated cmdclient and spec. Webclient doesn't need updating for this.

Renamed /rooms to /createRoom. Removed ability to PUT raw room IDs, and removed tests which tested that. Updated cmdclient and webclient.

Removed MessageRestServlet, use RoomSendEventRestServlet instead. Updated cmdclient, tests and webclient. All appears to work.

Renaming: /im/sync >> /initialSync. /rooms/$roomid/members/list >> /rooms/$roomid/members. /rooms$roomid/messages/list >> /room/$roomid/messages. Updated cmdclient, tests and webclient.

URL renaming: Room state keys now use the format /rooms/$roomid/state/$event_type/$state_key. cmdclient: Fixed double urlencoding on leave command. Stream from the END since START now produces an error on /events.

add in copyrights to everything, not just the synapse subdir, and add a copyrighter.pl whilst we're at it