fix(sdk): Do not update the LatestEventValue if its event ID matches the previous value

[Hywan]

This patch updates the logic to update a LatestEventValue. We still can't compare two LatestEventValue because the type doesn't implement PartialEq. However, we can use the EventId in some case.

It fixes #6381.

---

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

[codspeed]

Merging this PR will degrade performance by 40.62%

⚠️ 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]	165.7 ms	279 ms	-40.62%

---

_{Comparing Hywan:fix-issue-6381 (6214dd8) with main (9c28ee7)}

[codecov]

Codecov Report

❌ Patch coverage is 98.11321% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.82%. Comparing base (9c28ee7) to head (6214dd8).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...s/matrix-sdk/src/latest_events/latest_event/mod.rs	98.11%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6396      +/-   ##
==========================================
- Coverage   89.83%   89.82%   -0.01%     
==========================================
  Files         378      378              
  Lines      104214   104314     +100     
  Branches   104214   104314     +100     
==========================================
+ Hits        93622    93702      +80     
- Misses       7000     7016      +16     
- Partials     3592     3596       +4     

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[poljar]

Does this need two reviewers or what's going on?

[Hywan]

@poljar GitHub picked you once the PR was ready, but @bnjbvr also reviewed it while it was a draft.

[Hywan]

(have rebased to resolve the conflict)

[poljar]

Small tweak to the changelog entry required, looks good otherwise.