feat: PreDelete hooks support (Issue #13975)

[pedro-cs-ribeiro]

Closes #13975

This PR introduces PreDelete hooks for Argo CD. PreDelete hooks allow users to execute tasks before an application's resources are deleted, providing a way to perform graceful shutdowns, backup operations, or other cleanup tasks that should happen before resource deletion.

Implementation details:

The implementation follows the same pattern established for PostDelete hooks:

• Adds PreDeleteFinalizerName constant
• Implements Pre/UnSet/HasPreDeleteFinalizer methods
• Adds hook detection logic via isPreDeleteHook()
• Implements hook execution methods via executePreDeleteHooks() and cleanupPreDeleteHooks()
• Updates application controller to respect the proper deletion order

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Toolchain Guide
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

ArgoCD_PreDelete_Hook.mov

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[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.50%. Comparing base (0c6fa28) to head (418ff79).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
controller/appcontroller.go	62.79%	9 Missing and 7 partials ⚠️
controller/hook.go	87.30%	3 Missing and 5 partials ⚠️
pkg/apis/application/v1alpha1/types.go	60.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #22288      +/-   ##
==========================================
+ Coverage   62.46%   62.50%   +0.04%     
==========================================
  Files         351      351              
  Lines       49502    49602     +100     
==========================================
+ Hits        30919    31002      +83     
- Misses      15622    15630       +8     
- Partials     2961     2970       +9     

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[xrow]

Yesterday I was implementing a workaround because of this missing feature. Now I think holy sh*t cow there it is.

[pedro-cs-ribeiro]

@andrii-korotkov-verkada Thanks for the Review! I rebased the code correctly now and implemented some changes according to your review, please check.

[agaudreault]

Overall LGTM.

[pedro-cs-ribeiro]

Thanks for the review @agaudreault !

I just addressed all your comments and merged with the latest code, please take another look whenever you can.

[agaudreault]

LGTM. I think the current code is solid and a good foundation for the future. User experience can be adapted as the feature usage grows 👍