Allow running CMPs as standalone pods instead of sidecars

[jsoref]

Summary

CMPs should be able to be run in their own pods instead of relying on resources for the repo-server pod.

Motivation

Our nodes are resource constrained. We run a couple of CMPs in our repo-server pod and the resources required to make everyone happy exceed the node size. But 99% of the time none of the containers need any resources, not the argocd-repo-server itself and certainly not any of the CMPs.

Proposal

Whether the argocd-repo-server relies on a new CRD to define a new pod type and instantiates it, or whether it relies on some other magic is not something I care about. The end result should be a way to define a CMP such that argocd-repo-server can use it to resolve CMP handled content, and when CMPs aren't needed, their cost to the k8s cluster should be approximately 0.

See also #15006.

[jsoref]

I think that #14132 will address this