feat(mito): Implement file cache

[evenyag]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

This PR implements a cache for files in the WriteCache. The design is similar to the ReadCache.

The differences are

• This cache always caches the whole SST file as it serves as a write-through cache
• This cache doesn't read files from remote object stores

This cache has the following features:

• Caches files on local disk (the local store).
• Uses {region_id}.{file_id} as cache key and cached file name
• Uses an in-memory LRU cache as file index
• If the LRU cache removes the key, it also evicts the file on the local store.
• Recovers the file index from the local store

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

Refer to a related PR or issue link (optional)

• mito: Write cache for remote object store #2965

[codecov]

Codecov Report

Attention: 20 lines in your changes are missing coverage. Please review.

Comparison is base (b58296d) 85.54% compared to head (2ae9523) 85.05%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3022      +/-   ##
==========================================
- Coverage   85.54%   85.05%   -0.49%     
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  Files         793      794       +1     
  Lines      128447   128743     +296     
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- Hits       109880   109508     -372     
- Misses      18567    19235     +668     

[zhongzc]

I'm a little confused about the responsibilities. Cache is not responsible for storing files but deleting files, but it's not a big problem. LGTM

[killme2008]

LGTM