[githubgen] PR feedback follow-ups

[mowies]

This PR

• adds unit tests here and there to get coverage to a slightly better level
• refactors many parts of the code to make it better testable
• refactors parts of the code to be a bit less performant but much more readable (IMO of course)
• adds new flags to make the tool more suitable for general usage instead of just being focused on OTel Collector Contrib
  • caveat: the flags for now still have defaults that set everything for OTel Collector Contrib (this should probably change in another follow up to keep this PR from exploding)
• adds githubgen back to the released packages in versions.yaml
• addresses all feedback comments from feat: add githubgen tool #639
• fixes [githubgen] adopt change from contrib #667

Possible follow ups:

• move the whole CLI flag management to cobra so that flags can be sub-divided per sub-command (codeowners, issue-templates, distributions)
• if a default codeowner is provided, the tool should not exit with an error when a component doesn't have codeowners define, but it should rather continue with the default codeowners resolved this here because it's a requirement IMHO

[codecov]

Codecov Report

Attention: Patch coverage is 51.79856% with 67 lines in your changes missing coverage. Please review.

Project coverage is 51.19%. Comparing base (b29324c) to head (7e2fc41).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
githubgen/codeowners.go	64.86%	25 Missing and 1 partial ⚠️
githubgen/main.go	31.57%	26 Missing ⚠️
githubgen/issuetemplates.go	57.89%	8 Missing ⚠️
githubgen/distributions.go	12.50%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #655      +/-   ##
==========================================
+ Coverage   48.83%   51.19%   +2.36%     
==========================================
  Files          57       57              
  Lines        3387     3422      +35     
==========================================
+ Hits         1654     1752      +98     
+ Misses       1572     1507      -65     
- Partials      161      163       +2     

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[mx-psi]

Still need to look into some files, but some small comments

[mowies]

@dmathieu I addressed all feedback in this PR

[mowies]

i found some new issues with this PR i want to solve before merging, pls don't merge yet

[mx-psi]

Let me mark as draft until this is ready to merge

[mowies]

ok the PR should be ready now. i ran into some issues when testing this against the collector core repo with relative paths in codeowner files that were generated. Also, the default codeowners are used when none are defined in a component instead of fully erroring out.

[mowies]

new commits since previous reviews start at b518bbe

[mowies]

@atoulme @mx-psi @dmathieu pls re-review when you have time :)

[mx-psi]

@atoulme will merge this on Thursday unless you comment

[atoulme]

sorry didn't realize this was waiting on me, go for it

[jade-guiton-dd]

Would it be okay to include githubgen in the next release now that this is merged?

[mowies]

yes should be ok. i opened a draft release PR already #668