[prototype] merger, add functionality

[tarasmadan]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 57.77778% with 19 lines in your changes are missing coverage. Please review.

Project coverage is 61.1%. Comparing base (fdb4c10) to head (deb2a0f).
Report is 7 commits behind head on master.

❗ Current head deb2a0f differs from pull request most recent head d3e4c47. Consider uploading reports for the commit d3e4c47 to get more accurate results

Additional details and impacted files

Files	Coverage Δ
pkg/covermerger/repos.go	62.5% <0.0%> (-2.7%)	⬇️
pkg/covermerger/lines_matcher.go	81.2% <0.0%> (-18.8%)	⬇️
pkg/covermerger/covermerger.go	71.6% <68.4%> (+4.5%)	⬆️

... and 2 files with indirect coverage changes