Add support for _meta field to ILM policies

[dakrone]

We support the _meta key as an object that can contain any data in our component and composable index templates. We use this functionality to be able to give these objects descriptions and indicate whether they are managed by Elasticsearch.

We should add support for this _meta field to ILM policies themselves.

[elasticmachine]

Pinging @elastic/es-core-features (Team:Core/Features)

[gaobinlong]

@dakrone, can I work on the issue? I'm interested in ILM and have submitted several PRs for ILM.

[dakrone]

@gaobinlong certainly, that would be great, feel free to ping me if you need any assistance.

[dakrone]

This has been resolved in #73515, thanks again @gaobinlong