feat: Add function to check if cache contains a key

[Darkheir]

Add a new function allowing to check if the cache contains the given key

[janisz]

Do we need this func? We have Get

[Darkheir]

The main difference is that Get increases the hit score of the key while Contains doesn't.

I also find it more readable to do if !cache.Contains("key") than if _, err := cache.Get("foo"); errors.Is(err, bigcache.ErrEntryNotFound)

[cristaloleg]

SGTM

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.31%. Comparing base (e5c39b2) to head (6a482f4).
Report is 1 commits behind head on main.

❗ Current head 6a482f4 differs from pull request most recent head 29b0a38

Please upload reports for the commit 29b0a38 to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #382      +/-   ##
==========================================
+ Coverage   89.08%   89.31%   +0.23%     
==========================================
  Files          15       15              
  Lines         797      805       +8     
==========================================
+ Hits          710      719       +9     
  Misses         73       73              
+ Partials       14       13       -1     

Files	Coverage Δ
bigcache.go	93.18% <100.00%> (+0.81%)	⬆️
shard.go	92.22% <100.00%> (+0.20%)	⬆️

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[janisz]

Since @cristaloleg is fine with extending the interface let's merge it. Just one nitpic