Enhance ApplicationSet generator

[nerzhul]

Summary

Currently application set can generate various things, but it's only strings.

This doesn't permit to handle properly the arrays, like ignoreDifferences.

Motivation

See the way we currently do to use a big appset generator permitting to ignore one object difference with max 5 fields

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: cluster-main
spec:
  generators:
  - matrix:
      generators:
      - git:
          files:
          - path: '*/config.json'
          repoURL: https://git.repo/git
          revision: 'main'
      - clusters: {}
  template:
    metadata:
      name: '{{path[0]}}-{{name}}'
    spec:
      ignoreDifferences:
      - group: '{{ignoreDifferences.0.group}}'
        kind: '{{ignoreDifferences.0.kind}}'
        name: '{{ignoreDifferences.0.name}}'
        namespace: '{{ignoreDifferences.0.namespace}}'
        jsonPointers:
          - '{{ignoreDifferences.0.jsonPointers.0}}'
          - '{{ignoreDifferences.0.jsonPointers.1}}'
          - '{{ignoreDifferences.0.jsonPointers.2}}'
          - '{{ignoreDifferences.0.jsonPointers.3}}'
          - '{{ignoreDifferences.0.jsonPointers.4}}'

Proposal

I think it should be possible to put an array in config.json files and argo uses it for ignore differences. It's clearly harder for validation webhook to ensure it's always proper

[crenshaw-dev]

I think this is a duplicate of #11213.

Please lmk if that issue doesn't completely cover your use case!

[nerzhul]

clearly, thanks, i added a comment there