Description

Fixes #2073

This PR adds two features:

1. Media Library enables users to browse all the Active Storage attachments and update them.

2. Gallery for Trix and Rhino fields which enables a user to inject attachments in the body of the editor. The user can inject multiple files at once.

Screenshots

1. Media Library

2. WYSIWYG Gallery

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

Still to do:

• settle on controllers
• make pagination work on field gallery mode
• Improve modal styling (check if it looks good on field gallery mode)
• remove the "side-view" for the initial iteration. it was previously implemented but abandoned
• if attachments are disabled, the media library button is hidden in Trix field. That should be visible IMHO
• check other types of files (other than images)
  • check the representable support

Second iteration:

• Add "dropzone" style box to drop files in the gallery
• add search
• add filters
• media library as a field. show it like we show the associations