General: Extract the code editor settings from `wp_enqueue_code_editor()`.

They're now returned by a new function, `wp_get_code_editor_settings()`, so they can be reused by the block editor.

Props pento.

Merges [43761] to trunk.

Fixes #45127.
Built from https://develop.svn.wordpress.org/trunk@44121


git-svn-id: https://core.svn.wordpress.org/trunk@43951 1a063a9b-81f0-0310-95a4-ce76da25c4cd