feat: introduce tiered cache module

[MrCroxx]

What changes were proposed in this pull request?

Introduce the tiered cache module for further usage.

Which issues is this PR related to?

#171

How was this patch tested?

Passed unit tests. The module is not integrated into the RunKV storage engine for now.

Will this help MrCroxx run or graduate?

Hopefully.

[codecov]

Codecov Report

Merging #177 (52a3fa0) into main (383ce7a) will increase coverage by 3.51%.
The diff coverage is 88.25%.

@@            Coverage Diff             @@
##             main     #177      +/-   ##
==========================================
+ Coverage   81.35%   84.86%   +3.51%     
==========================================
  Files          94      100       +6     
  Lines        9212    11022    +1810     
==========================================
+ Hits         7494     9354    +1860     
+ Misses       1718     1668      -50     

Impacted Files	Coverage Δ
storage/src/lib.rs	100.00% <ø> (ø)
storage/src/tiered_cache/file_cache/error.rs	0.00% <0.00%> (ø)
wheel/src/lib.rs	91.02% <ø> (ø)
storage/src/tiered_cache/mod.rs	21.68% <21.68%> (ø)
storage/src/tiered_cache/file_cache/utils.rs	75.00% <75.00%> (ø)
storage/src/tiered_cache/file_cache/cache.rs	78.45% <78.45%> (ø)
storage/src/lsm_tree/components/sstable_store.rs	83.01% <80.00%> (-1.25%)	⬇️
storage/src/tiered_cache/file_cache/file.rs	83.25% <83.25%> (ø)
storage/src/lsm_tree/components/skiplist/list.rs	85.71% <88.88%> (-0.05%)	⬇️
storage/src/tiered_cache/file_cache/mod.rs	88.88% <88.88%> (ø)
... and 20 more

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