[ILM] Allow ILMs to be applied to Component Templates

[nicpenning]

Describe the feature:
With more and more integrations by Elastic we are needing to apply custom ILMs to the @custom component templates. When you go to add an ILM to an Index Template, that is the only option.

Describe a specific use case for the feature:
I need to apply custom ILMs to out of the box integrations from Elastic and it would be great to create a new ILM and apply it to X component template.

[elasticmachine]

Pinging @elastic/kibana-management (Team:Kibana Management)

[alisonelizabeth]

Thanks @nicpenning for opening.

I think this is somewhat related to #172683

[nicpenning]

Yes. That does sounds similar. I couldn't find that issue specifically when creating this one. Thanks!

Mine does sound a little more direct on the goal, however :) I have a picture!