Data track schema metadata

[ladvoc]

Adds support for associating schema metadata with a published data track and storing/retrieving schema definitions.

Schema storage is built on-top of data blobs, a general purpose mechanism for storing large (in the order of KBs), arbitrary data blobs in a room:

• Protocol: Data blobs protocol#1595
• SFU implementation: https://github.com/livekit/livekit/tree/raja_async_attributes

Protocol additions for schema metadata:

• Data tracks schema metadata protocol#1553

[github-actions]

Changeset

The following package versions will be affected by this PR:

Package	Bump
livekit	patch
livekit-datatrack	patch
livekit-ffi	patch

[ladvoc]

For local testing:

• Use this SFU branch: https://github.com/livekit/livekit/tree/ladvoc/schema-metadata
• Build and run with data blobs support enabled: LIVEKIT_CONFIG="enable_participant_data_blob: true" ./bin/livekit-server --dev