Declare support for Matrix v1.11

[turt2live]

Previous version: #17021
Changelog (with clarifications included): https://spec.matrix.org/v1.11/changelog/#v111

Client-Server API

Deprecations

• Authentication using a query string is now deprecated, as per MSC4126. The Authorization header should be used instead. (#1808)
  • No-op
• Use of the /_matrix/media/* endpoints is now deprecated. New, authenticated, endpoints are available instead. (#1858)
  • See below

New Endpoints

• GET /_matrix/client/v1/media/config (#1858)
  • Made stable in Support MSC3916 by adding a federation /thumbnail endpoint and authenticated _matrix/client/v1/media/thumbnail endpoint #17388
  • Support MSC3916 by adding unstable media endpoints to _matrix/client #17213
• GET /_matrix/client/v1/media/download/{serverName}/{mediaId} (#1858)
  • Support MSC3916 by adding _matrix/client/v1/media/download endpoint #17365
• GET /_matrix/client/v1/media/download/{serverName}/{mediaId}/{fileName} (#1858)
  • Support MSC3916 by adding _matrix/client/v1/media/download endpoint #17365
• GET /_matrix/client/v1/media/preview_url (#1858)
  • Made stable in Support MSC3916 by adding a federation /thumbnail endpoint and authenticated _matrix/client/v1/media/thumbnail endpoint #17388
  • Support MSC3916 by adding unstable media endpoints to _matrix/client #17213
• GET /_matrix/client/v1/media/thumbnail/{serverName}/{mediaId} (#1858)
  • Support MSC3916 by adding a federation /thumbnail endpoint and authenticated _matrix/client/v1/media/thumbnail endpoint #17388
  • Support MSC3916 by adding unstable media endpoints to _matrix/client #17213

Backwards Compatible Changes

• Add support for muting in VoIP calls, as per MSC3291. (#1755)
  • No-op (event change)
• Add optional animated query string option to GET /thumbnail, as per MSC2705. (#1757)
  • The MSC has provision for servers which don't support animation, so we're compliant here. Future support would be Thumbnailing animated GIFs (or showing they're an animation) (SYN-251) #1278
• Specify terms of services at registration, as per MSC1692. (#1812)
  • Support has been in Synapse forever
• Add support for mathematical messages, as per MSC2191. (#1816)
  • No-op (client markup)
• Do not require UIA when first uploading cross-signing keys, as per MSC3967. (#1828)
  • Implementation of MSC3967: Don't require UIA for initial upload of cross signing keys matrix-org/synapse#15077
  • Made stable in Enable cross-signing key upload without UIA #17284
• Add the new unsigned.membership property to events, as per MSC4115. (#1847)
  • Add support for MSC4115 #17104
  • Made stable in Include user membership on events #17282
• Media downloads and thumbnails are now authenticated, as per MSC3916. (#1858)
  • See above
• Some media endpoints are now consistently under /_matrix/client/{version}/media/* instead of /_matrix/media/*, as per MSC3916. (#1858)
  • See above

Server-Server API

Deprecations

• Use of the Client-Server API /_matrix/media/* endpoints is now deprecated. New, authenticated, endpoints are available instead. (#1858)
  • Fallback handled in Support MSC3916 by adding _matrix/client/v1/media/download endpoint #17365

New Endpoints

• GET /_matrix/federation/v1/media/download/{mediaId} (#1858)
  • Made stable in Support MSC3916 by adding _matrix/client/v1/media/download endpoint #17365
  • Chain from Re-introduce federation /download endpoint #17350
• GET /_matrix/federation/v1/media/thumbnail/{mediaId} (#1858)
  • Support MSC3916 by adding a federation /thumbnail endpoint and authenticated _matrix/client/v1/media/thumbnail endpoint #17388

Backwards Compatible Changes

• Media downloads and thumbnails are now authenticated, as per MSC3916. (#1858, #1869)
  • See above

Identity Service API

Deprecations

• Authentication using a query string is now deprecated, as per MSC4126. The Authorization header should be used instead. (#1808)
  • No-op (all call sites I could find use the Authorization header already)

[turt2live]

So... we're ready to do this, which is neat. I'll open a PR.

Only blocker is #17388 which has feedback, but is approved.