feat: Add repository target to ruleset

[stevehipwell]

This PR adds support for rulesets targeting repositories (otherwise known as repository management policies).

@gmlewis I also removed the usage of reflect in favour of a more manual pattern.

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.36%. Comparing base (841abae) to head (21fb8df).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
github/rules.go	71.42%	10 Missing and 10 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3850      +/-   ##
==========================================
- Coverage   92.46%   92.36%   -0.11%     
==========================================
  Files         199      199              
  Lines       14240    14308      +68     
==========================================
+ Hits        13167    13215      +48     
- Misses        884      894      +10     
- Partials      189      199      +10     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[gmlewis]

Thank you, @stevehipwell!
LGTM.
Awaiting second LGTM+Approval from any other contributor to this repo before merging.

cc: @alexandear - @zyfy29

[stevehipwell]

@gmlewis sorry for overwriting the last commit, force of habit.

[stevehipwell]

@gmlewis this PR requires #3853 to be merged first to fix the linting.

[stevehipwell]

@gmlewis I've rebased this PR onto the linter changes.

[gmlewis]

Thank you, @alexandear!
Merging.

[stevehipwell]

@gmlewis this functionality is something I'd really appreciate being released soon if at all possible?

[gmlewis]

@gmlewis this functionality is something I'd really appreciate being released soon if at all possible?

OK, I'll work on cutting a release today.

[gmlewis]

@stevehipwell - this is now available in v80.0.0:
https://github.com/google/go-github/releases/tag/v80.0.0