feat: add room versions to HomeserverCapabilities

[Susurrus]

Expose room versions as well, which weren't originally included in !6371. I'm not clear why, but this is used by Fractal, so updating to the newest SDK is a bit annoying without this. See https://gitlab.gnome.org/World/fractal/-/merge_requests/2168 for the code changes for that upgrade.

I think this can reuse the existing CHANGELOG entry since it's not super specific.

• I've documented the public API Changes in the appropriate CHANGELOG.md files.
• This PR was made with the help of AI.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.81%. Comparing base (1f3dea7) to head (cfa54fc).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...s/matrix-sdk/src/client/homeserver_capabilities.rs	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6413      +/-   ##
==========================================
- Coverage   89.85%   89.81%   -0.05%     
==========================================
  Files         378      378              
  Lines      103777   103785       +8     
  Branches   103777   103785       +8     
==========================================
- Hits        93248    93212      -36     
- Misses       6957     6984      +27     
- Partials     3572     3589      +17     

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[codspeed-hq]

Merging this PR will degrade performance by 49.83%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 49 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	Restore session [memory store]	111.7 ms	222.6 ms	-49.83%

---

_{Comparing Susurrus:room_versions (39f48f4) with main (1f3dea7)}

[bnjbvr]

Thanks! Just a tiny comment around the changelog entry, and we should be good to go!

[bnjbvr]

Thank you!