Option to allow patches through configMap

[ndemeshchenko]

In certain complex setup for multi cluster setups, there are multiple levels of kustomization.
For example, top level kustomization cluster-addons creates multiple different kustomization from external repo. Since there will be different kustomization reconcilers for each "addon", it's not possible to patch certain resources (from that external repo) from top level kustomization.

Having configmap with patches and instruction where to apply it, would solve this.