[epic] Fully decouple PromFed binary from `helm-controller`

[mallardduck]

This is an epic to track the helm-controller decoupling effort.

The original plan was presented with 2 options here, now that we have picked an obvious option we can track the "full project" here.

• 2.14.0:
  • Introduce new mechanism to run Helm Controller alongside PromFed via Helm chart - @diogoasouza working on this
  • Document migration path (in values file and docs, etc)
  • Deprecate the version of Helm Controller inside of PromFed
• 2.15:
  • Remove the binary built-in version of Helm Controller leaving only the Chart option

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This is just a rough idea, will need @prachidamle and @Jono-SUSE-Rancher to help verify acceptable timelines.