feat: support dedicated cleaner thread for in-memory cache

[MrCroxx]

What's changed and what's your intention?

Please explain IN DETAIL what the changes are in this PR and why they are needed. :D

TODO: WIP

Checklist

• I have written the necessary rustdoc comments
• I have added the necessary unit tests and integration tests
• I have passed make all (or make fast instead if the old tests are not modified) in my local environment.

Related issues or PRs (optional)

#653

[codecov]

Codecov Report

Attention: Patch coverage is 16.98113% with 44 lines in your changes missing coverage. Please review.

Project coverage is 82.22%. Comparing base (aab45f0) to head (b188bd0).

Files	Patch %	Lines
foyer-memory/src/cleaner.rs	0.00%	27 Missing ⚠️
foyer/src/hybrid/builder.rs	0.00%	8 Missing ⚠️
foyer-memory/src/cache.rs	22.22%	7 Missing ⚠️
foyer-bench/src/main.rs	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #654      +/-   ##
==========================================
- Coverage   82.66%   82.22%   -0.44%     
==========================================
  Files          66       67       +1     
  Lines        8115     8164      +49     
==========================================
+ Hits         6708     6713       +5     
- Misses       1407     1451      +44     

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