Cache REST controller references on their associated post type object to prevent unnecessary controller re-instantiation, which previously caused "rest_prepare_{$post_type}" and "rest_{$post_type}_query" to run twice per request. Props TimothyBlynJacobs, patrelentlesstechnologycom. Fixes #45677. git-svn-id: https://develop.svn.wordpress.org/trunk@46272 602fd350-edb4-49c9-b593-d223f7449a82