feat: git tag step + tag support for git push

[fuskovic]

Closes: #5737

Demo

tag+push-demo.mov

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[codecov]

Codecov Report

❌ Patch coverage is 49.47368% with 48 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.24%. Comparing base (e8877b6) to head (b002dc5).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/promotion/runner/builtin/git_tagger.go	55.55%	18 Missing and 6 partials ⚠️
pkg/controller/git/work_tree.go	28.00%	17 Missing and 1 partial ⚠️
pkg/gitprovider/registry.go	0.00%	3 Missing ⚠️
pkg/controller/git/mock_repo.go	0.00%	2 Missing ⚠️
pkg/promotion/runner/builtin/git_pusher.go	90.90%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5785      +/-   ##
==========================================
- Coverage   56.25%   56.24%   -0.01%     
==========================================
  Files         451      452       +1     
  Lines       37840    37959     +119     
==========================================
+ Hits        21286    21350      +64     
- Misses      15293    15340      +47     
- Partials     1261     1269       +8     

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[krancour]

Total aside and note to self... I realize this code wasn't ever refactored to use the PredicateBasedRegistry. Out of scope for this PR, but I should fix that.

[fuskovic]

@krancour I've pushed the suggested changes and updated the demo in the PR description to show the commit information. Some notes:

• The commit URL only populates when the provider is set, so I've updated the output to omit that key/value pair entirely if provider is not provided or if it is and we fail to get the commit URL.

• You'll notice in the current demo the branch is included in the output for git pushing tags. I'm wondering if we want to keep that behavior or have tag and branch be mutually exclusive in the output?

Alternatively, we can always set all output keys unconditionally so they can always be referenced dynamically in other steps (regardless if they're empty).

Thoughts?