Describe the feature:

System indices have the convention of starting with a dot (.). This makes isolation of stack indices from user indices quick and simple.

We don't do the same with ILM policies (or other stack managed resources), for example https://github.com/elastic/elasticsearch/blob/master/x-pack/plugin/core/src/main/resources/watch-history-ilm-policy.json

I'd like to propose that we extend the dot convention to ILM policies or potentially other elasticsearch resources that may contain a mix of both stack and user managed entries.