Fixes #37883 - halt if remote DB does not own EVR

[ianballou]

Checks if the postgres user owns the evr extension. If it does, halt the foreman-installer and report an error with the command to run to fix the permissions.

Also check if postgres is the foreman DB owner. In that case, don't do anything because the migration will succeed.

There's no provision if the admin user is called something other than postgres. Should there be?