fix: calculate SSA diffs with smd.merge.Updater

[leoluz]

This PR introduces a different strategy to calculate diffs while using server-side apply.
The new approach will delegate all diff calculation logic to the merge.Updater.Apply function in the structured-merge-diff k8s library.

The previous implementation was naive and was missing many edge cases already addressed by merge.Updater.Apply.

However, merge.Updater.Apply has a hard to solve dependencies requirements. In order to provide the necessary dependencies, this PR borrows code from the k8s api-server which is properly documented in the pkg.diff.internal.fieldmanager package (see doc.go).

Fix argoproj/argo-cd#10627

[codecov]

Codecov Report

Base: 55.40% // Head: 55.46% // Increases project coverage by +0.06% 🎉

Coverage data is based on head (6a5b081) compared to base (3951079).
Patch coverage: 64.15% of modified lines in pull request are covered.

❗ Current head 6a5b081 differs from pull request most recent head b585433. Consider uploading reports for the commit b585433 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #467      +/-   ##
==========================================
+ Coverage   55.40%   55.46%   +0.06%     
==========================================
  Files          41       41              
  Lines        4480     4504      +24     
==========================================
+ Hits         2482     2498      +16     
- Misses       1807     1813       +6     
- Partials      191      193       +2     

Impacted Files	Coverage Δ
pkg/diff/diff.go	61.09% <64.15%> (+0.21%)	⬆️

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[crenshaw-dev]

lgtm! Gonna ask @alexmt for a review, mostly for awareness.

[crenshaw-dev]

Leo spoke with Alex about this change at ArgoCon, so I'm comfortable merging it.