feat(appset): Support AWS CodeCommit in ApplicationSet controller (Alpha)

[jzhn]

What

Closes #13496 . This PR implements initial support for AWS CodeCommit as scmProvider in ApplicationSet controller. Please refer to the linked issue for the original enhancement proposal.

Additional considerations

Tests

Although unit tests coverage is decent, we can only go so far testing AWS APIs. I've manually tested the build in my ArgoCD environment to verify most scenarios supported by this PR. However, if there's any AWS test infrastructure for ArgoCD project, we could further add integration tests to gain additional confidence.

Original Notes

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[codecov]

Codecov Report

Patch coverage: 75.55% and project coverage change: +0.16 🎉

Comparison is base (4c982b2) 49.09% compared to head (d28157b) 49.25%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #13579      +/-   ##
==========================================
+ Coverage   49.09%   49.25%   +0.16%     
==========================================
  Files         250      251       +1     
  Lines       43248    43518     +270     
==========================================
+ Hits        21231    21435     +204     
- Misses      19889    19949      +60     
- Partials     2128     2134       +6     

Impacted Files	Coverage Δ
applicationset/generators/scm_provider.go	33.53% <0.00%> (-1.25%)	⬇️
.../apis/application/v1alpha1/applicationset_types.go	28.57% <ø> (ø)
...icationset/services/scm_provider/aws_codecommit.go	77.27% <77.27%> (ø)

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[crenshaw-dev]

lgtm!

This implementation is slightly more complex than other SCM providers. I think it would be a great candidate to externalize to a plugin generator in the future. But for now, code looks good, happy to have it upstream.