extract cachestats to record cache stats

[libotony]

Description

This PR moves cachestats to a standalone file to make it available globally and applies cachestats to muxdb and chain to track cache miss/hit.

A notable change here is this PR changes the metric type in package chain to GaugeVec

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also
list any relevant details for your test configuration

• Test A
• Test B

Test Configuration:

• Go Version:
• Hardware:
• Docker Version:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• New and existing E2E tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 55.66038% with 47 lines in your changes missing coverage. Please review.

Project coverage is 60.79%. Comparing base (dcea741) to head (6f39d92).

Files with missing lines	Patch %	Lines
muxdb/internal/trie/cache.go	0.00%	23 Missing ⚠️
chain/repository.go	55.88%	12 Missing and 3 partials ⚠️
runtime/runtime.go	70.96%	8 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #924      +/-   ##
==========================================
+ Coverage   60.69%   60.79%   +0.10%     
==========================================
  Files         219      220       +1     
  Lines       23383    23414      +31     
==========================================
+ Hits        14192    14235      +43     
+ Misses       8028     8010      -18     
- Partials     1163     1169       +6     

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[darrenvechain]

Should we put this in metrics dir?

[otherview]

Captured in a ticket 👍