feat(cache/unstable): add stats to LruCache

[tomas-zijdemans]

Adding stats to the cache is nice for observability, logging, etc. I plan to add the same to TTL cache.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.41%. Comparing base (21ba810) to head (76a4c47).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7069   +/-   ##
=======================================
  Coverage   94.41%   94.41%           
=======================================
  Files         630      630           
  Lines       50435    50461   +26     
  Branches     8928     8930    +2     
=======================================
+ Hits        47616    47642   +26     
  Misses       2249     2249           
  Partials      570      570           

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