feat(client): Support for RTC transports discovery

[BillCarsonFr]

RTC transport discovery has now a new authenticated end-point on the homeserver GET /_matrix/client/v1/rtc/transports

This PR add supports for that via a new client API Client::rtc_transports, it uses the existing cache mecanism used by similar APIs (well-known, supported_version). I used a similar pattern.

The old rtc_foci endpoint has been renamed to wellknown_rtc_transport and should only be used as fallback if new endpoint is not supported

• I've documented the public API changes in the appropriate changelog files (see Writing changelog entries).
• This PR was made with the help of AI.

Signed-off-by:

[codspeed-hq]

Merging this PR will not alter performance

✅ 50 untouched benchmarks

---

_{Comparing valere/rtc/msc4143_rtc_discovery (d3f4261) with main (c1db376)}

[codecov]

Codecov Report

❌ Patch coverage is 84.09091% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.01%. Comparing base (c1db376) to head (d3f4261).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
crates/matrix-sdk/src/client/mod.rs	84.09%	17 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6789      +/-   ##
==========================================
- Coverage   90.02%   90.01%   -0.01%     
==========================================
  Files         405      405              
  Lines      113627   113746     +119     
  Branches   113627   113746     +119     
==========================================
+ Hits       102290   102386      +96     
- Misses       7463     7476      +13     
- Partials     3874     3884      +10     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[jmartinesp]

LGTM, just wondering if it's a good idea to rename the existing method if it's being deprecated anyway. I guess it'll mean a migration will be needed and it will force clients to notice the replacement.

[BillCarsonFr]

LGTM, just wondering if it's a good idea to rename the existing method if it's being deprecated anyway. I guess it'll mean a migration will be needed and it will force clients to notice the replacement.

Maybe I can keep the old name like that?

#[deprecated = "Use `Client::rtc_transports` instead"]
pub async fn rtc_foci(&self) -> HttpResult<Vec<RtcTransport>> {
    self.well_known_rtc_transports()
}