feat: Supported set metadata annotations with argocd-util app generate-spec command

[takumakume]

Hello!

Added support for set metadata annotations with the argocd-util app generate-spec command.
My use case is to generate Annotations for use with the ArgoCD Image Updater.

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[codecov]

Codecov Report

Merging #6633 (eec0247) into master (7149e35) will increase coverage by 0.00%.
The diff coverage is 35.00%.

@@           Coverage Diff           @@
##           master    #6633   +/-   ##
=======================================
  Coverage   41.29%   41.30%           
=======================================
  Files         156      156           
  Lines       20688    20701   +13     
=======================================
+ Hits         8543     8550    +7     
- Misses      10937    10943    +6     
  Partials     1208     1208           

Impacted Files	Coverage Δ
cmd/argocd-util/commands/app.go	31.30% <0.00%> (-0.28%)	⬇️
cmd/argocd/commands/app.go	0.00% <0.00%> (ø)
cmd/util/app.go	36.87% <77.77%> (+1.05%)	⬆️

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[jannfis]

Thanks @takumakume for this PR. I agree that this would be useful.

However, I think the command line option should be moved to a different part in the code. AddAppFlags() sets flags for the .spec part of the Application resource, not for its .metadata section.

I think the right place - despite some redundancy - would be here and here

[takumakume]

@jannfis Thank you for the review!
That's right.
I removed this option from AddAppFlags() and changed it to the location indicated.

[takumakume]

I implemented two more

• fix: set an empty value if there is no = in --annotations
• docs: added an example --annotations are = delimited

Please check

[jannfis]

LGTM, thank you!