feat: support kustomize image newName override

[jessesuen]

This is the manual cherry-pick of #2470 to the release-0.8 branch. Automatic cherry-pick failed because of codegen conflicts since the backport involves a change to the API type.

[netlify]

✅ Deploy Preview for docs-kargo-akuity-io canceled.

Name	Link
🔨 Latest commit	422eea5
🔍 Latest deploy log	https://app.netlify.com/sites/docs-kargo-akuity-io/deploys/66ce3a2c4d3833000839c6e2

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 46.72%. Comparing base (dc2c81b) to head (422eea5).
Report is 1 commits behind head on release-0.8.

Files	Patch %	Lines
internal/controller/promotion/kustomize.go	60.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-0.8    #2471      +/-   ##
===============================================
- Coverage        46.72%   46.72%   -0.01%     
===============================================
  Files              246      246              
  Lines            17747    17750       +3     
===============================================
+ Hits              8292     8293       +1     
- Misses            9025     9026       +1     
- Partials           430      431       +1     

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