Add Vector Database (VDB) Automator for Entity Reference Fields

This is a really good idea!

Since I added code myself here, I would ask for someone else to do the final review if possible. If no one does it before Wednesday, it gets merged (its just new automator types, so won't break anything else).

Added some queries and noted missing documentation.

Thanks Paul - I fixed your comments and realized we also needed to add checks for if indexes are disabled or not.

LGTM :)

I added that you also need "administer search_api" permission to see the Automators, otherwise someone that has field access could use this as a backdoor to access content they are not privileged to see.

I Also added a warning message on this field, when setting it up since it will have the same potential permissions override effect similar to what the Views Automator would have.

"⚠️ Note that this will save the data found in this field and that any user that has access to view this field will see the content, independent on content permissions or index permissions."

Merging this.