Add more rich stats

[maypok86]

Description

Added collection of additional statistics, such as:

• Number of rejected sets
• Number of evicted entries
• Sum of costs of evicted entries

Related issue(s)

• Resolves Feature: Adding more rich stats #57

✅ Checklist for your Pull Request

Related changes (conditional)

• Tests

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from
    silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README

• Public contracts

  • My changes doesn't break project license.

Stylistic guide (mandatory)

• My code complies with the styles guide.

• My commit history is clean (only contains changes relating to my
  issue/pull request and no reverted-my-earlier-commit changes) and commit
  messages start with identifiers of related issues in square brackets.

  Example: [#42] Short commit description

  If necessary both of these can be achieved even after the commits have been
  made/pushed using rebase and squash.

Before merging (mandatory)

• Check target branch of PR is set correctly

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.87500% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 95.63%. Comparing base (c66ac1f) to head (9e82d9a).

Files	Patch %	Lines
stats.go	93.54%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #61   +/-   ##
=======================================
  Coverage   95.62%   95.63%           
=======================================
  Files          22       23    +1     
  Lines        1235     1282   +47     
=======================================
+ Hits         1181     1226   +45     
- Misses         36       37    +1     
- Partials       18       19    +1     

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