Enforce media type specification for bulk uploading and improve UI/UX
Summary
This merge request addresses the primary issue of specifying a target media bundle for bulk upload while also providing an improved user-experience and ensuring that a user can't upload the wrong file extensions for the specified media type.
What's Included?
- Requires selection of the media type bundle before the dropzone widget is displayed
- Sets the allowed extensions for the dropzone widget based on the selected bundle
- Provides a per-media type route for bulk upload in addition to the regular one
- Adds a local action to the parent media add page as well as each media type add form for convenience
Closes #3462189