[Tagging] View/edit tags for a library component

[bradenmacdonald]

"As a Content Author, I can add/delete tags to content components (text blocks, video blocks, problem blocks) in a v2 Library."

"As a Content author, I can view tags that have already been added to content components in a v2 Library."

"As a Content Author, I expect that the experience to view, add and delete tags to content components mirrors the UI and experience when I view, add and delete tags to component xblocks on a Unit Page in a course."

Acceptance Criteria

1. From the new libraries MFE, I can select "Manage Tags" for any library component
   

In the library authoring MFE, it would look more like this:

2. The existing "Delete" icon should be moved to become a "Delete" item in the three dots menu.

3. Clicking "Manage Tags" opens the tagging drawer with the same tag viewing and editing functionality as units and course components have.

4. I can add/remove tags using the tagging drawer.

5. Components that have at least one tag display the total tag count as a clickable button, just like on the unit page:

Note: this is just showing where the "tag count button" goes in the new MFE. This is not how it should look:

It should look something more like this, but in the style of the new MFE:

5. For now this can just open the tag drawer in an iframe, but based on [Tagging] Discovery: Move the library-authoring MFE into the course-authoring MFE #164 we'll find a better way to integrate it.

6. This is all for v2 libraries only; no need to support v1. The library URL/ID should start with lib:, which indicates a v2 library.