Add an abstraction of the gallery code in `media-editor.js` called `wp.media.collection`. This will be the basis for parsing `[gallery]`-like shortcodes in the media editor (thing playlists, collections of PDFs, etc).

There are currently no instances of this. Those will be forthcoming.

See #26631.


Built from https://develop.svn.wordpress.org/trunk@27212


git-svn-id: http://core.svn.wordpress.org/trunk@27069 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Replace the current `wp.media.gallery` instance in `media-editor.js` with one that leverages `wp.media.collection`.

See #26631.


Built from https://develop.svn.wordpress.org/trunk@27213


git-svn-id: http://core.svn.wordpress.org/trunk@27070 1a063a9b-81f0-0310-95a4-ce76da25c4cd
In `media-views.js`, add `wp.media.controller.CollectionAdd` and `wp.media.controller.CollectionEdit` to provide an abstraction for Add and Edit screens in the media modal for collection-type things.

There are currently no instances of this. Those will be forthcoming.

See #26631.


Built from https://develop.svn.wordpress.org/trunk@27214


git-svn-id: http://core.svn.wordpress.org/trunk@27071 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Register `wp.media.controller.GalleryEdit` and `wp.media.controller.GalleryAdd` using the new `wp.media.controller.Collection*` abstraction code.

See #26631.


Built from https://develop.svn.wordpress.org/trunk@27215


git-svn-id: http://core.svn.wordpress.org/trunk@27072 1a063a9b-81f0-0310-95a4-ce76da25c4cd