[Tagging] Show tag count for each tagged component on the Unit Page

[bradenmacdonald]

On the unit page, when a component (XBlock) has at least 1 tag, the tag count button should appear, just like for units on the course outline page. Clicking it should open the tag drawer.

Should have the same button as seen on units on the outline:

Acceptance criteria

1. Components with no tags do not display the button
2. Components with 1+ tag(s) do display the button
3. The tag count for all the components on the page is loaded at once. (use , to separate component IDs with this API)
4. Update the wiki page at https://openedx.atlassian.net/wiki/spaces/COMM/pages/3866689562/New+Additions+to+the+Course+Unit+Page to mention this new feature.

[bradenmacdonald]

FYI @jmakowski1123 @ali-hugo

[jmakowski1123]

@bradenmacdonald , is the prior art at the unit level enough to implement this, or do you need a mock?

[bradenmacdonald]

@jmakowski1123 @ali-hugo Here's what it would look like if we basically copy the code from the outline onto the unit page. If this looks good, we'll go with it; if you want something that looks different, a mock would be helpful.

Note for devs: for this mock, I copied the <li> code and had to change the <a> to a button.btn-default.action-button to get it to look OK.

[ali-hugo]

@bradenmacdonald What you have in the screenshot above is perfect. I've updated the design files to match.