feat(sync): Allow setting a custom Sliding Sync connection ID and timeline limit on RoomListService

[Johennes]

This allows setting the roomlist service's connection ID and timeline limit over FFI. We've found this to be helpful when using the service from an iOS share extension simultaneously to the main app.

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

[codspeed-hq]

Merging this PR will improve performance by 68.28%

⚠️ 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 improved benchmark
✅ 49 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	Restore session [memory store]	282 ms	167.6 ms	+68.28%

---

_{Comparing Johennes:johannes/sync-service-customisation (5d2c04c) with main (acda2e8)}

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.92%. Comparing base (acda2e8) to head (69520be).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
crates/matrix-sdk-ui/src/sync_service.rs	70.00%	8 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6289   +/-   ##
=======================================
  Coverage   89.91%   89.92%           
=======================================
  Files         374      374           
  Lines      102613   102651   +38     
  Branches   102613   102651   +38     
=======================================
+ Hits        92267    92307   +40     
- Misses       6783     6790    +7     
+ Partials     3563     3554    -9     

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[Hywan]

Thank you for the contribution.

We've found this to be helpful when using the service from an iOS share extension simultaneously to the main app.

Why is it useful? Why do you need a different name?

[Johennes]

Why is it useful? Why do you need a different name?

We've ran into what we think is interference between the main app sync and the sync from our share extension where both tread on the same pos simultaneously then leading to an infinite loop where one of them keeps making requests with invalid positions.

IIUC sharing the position isn't fully guarded by the cross-process lock, so maybe this is why.

//.share_pos() // TODO: This is racy, needs cross-process lock :')