feat: introduce fs abstraction

[eddycharly]

Explanation

Introduce fs abstraction.

[eddycharly]

/cherry-pick release-0.2

[codecov]

Codecov Report

Attention: Patch coverage is 31.68317% with 69 lines in your changes missing coverage. Please review.

Project coverage is 66.17%. Comparing base (7545f46) to head (2b08cdc).

Files with missing lines	Patch %	Lines
pkg/utils/fs/getter.go	10.44%	60 Missing ⚠️
pkg/utils/fs/check.go	28.57%	3 Missing and 2 partials ⚠️
pkg/commands/test/command.go	62.50%	2 Missing and 1 partial ⚠️
pkg/utils/fs/discover.go	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2088      +/-   ##
==========================================
- Coverage   66.85%   66.17%   -0.68%     
==========================================
  Files         138      139       +1     
  Lines        6628     6714      +86     
==========================================
+ Hits         4431     4443      +12     
- Misses       1867     1936      +69     
- Partials      330      335       +5     

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