Add tags to media items

As a content author
I want to be able to tag media items (documents, images etc)
So that I could easily search for items by tags

AC1 - Media tags vocabulary
GIVEN I’m a Content author
WHEN I navigate to Media tags vocabulary (civictheme_media_tags)
THEN I can create/edit/delete tags

AC2 - Tagging media items with Media tags
GIVEN I’m a Content author
WHEN I create any of the media items
THEN I can specify one or more media tags
AND I can create new media tags (in the same UI)

AC3 - Searching through Media Library using Media tags
GIVEN I’m a Content author
WHEN I go to Content → Media page
AND I specify one or more media tags parts (comma delimited) in the search filter
THEN I can filter media items by the specified media tags

1. Create Media tags (civictheme_media_tags) vocabulary

2. Add permissions for the Content author and Site administrator roles to perform CRUD operations on terms (but not the vocabulary).

3. Add Behat tests for permissions

4. Add entity reference Media tags ( field_m_media_tags ) field to each media entity:

   1. Set it to allow creating new tags.

   2. Use autocomplete widget

5. Update existing Behat tests for fields on media entities

6. Create a clone of vanilla Drupal Media view and store it as optional config in theme (leave the name as-is). Adjust filters to show the `Media tags` filter and allow to match on partial tag matches.

7. Implement an additional settings provisioning option to replace Media view with the one shipped in CT configuration.

8. Add a Behat test that would be checking that a Content->Media page has the required filters and can be searched through.

9. Create a clone of vanilla Drupal Media library view and store it as optional config in theme (leave the name as-is). Adjust filters to show the `Media tags` filter and allow to match on partial tag matches.

10. Implement an additional settings provisioning option to replace Media library using the one shipped with configuration.

11. Add a Behat test that would be checking that a media library has the required filters and can be searched through.