Enable granularity for which controllers to run

[enxebre]

/kind feature

Describe the solution you'd like
As a cluster service provider managing a multi-tenant environment I would like to setup my capi controllers to watch only well known targeted resources and do not run unnecessary controllers. E.g If I'm targeting rosa/eks clusters I don't need to run the AWSmachine or the AWSCluster controllers

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster-api-provider-aws version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[nrb]

/triage accepted