What is the problem?
Before this change, we were relying on the `/tags` endpoint which
returned all the tags that are visible to a give user on the site leading to potential performance problems.
The attribute keys of the response also changes based on the `tags_listed_by_group` site setting.
What is the fix?
This commit fixes the problems listed above by creating a dedicate `#list` action in the
`TagsController` to handle the listing of the tags in the edit
navigation menu tags modal. This is because the `TagsController#index`
action was created specifically for the `/tags` route and the response
body does not really map well to what we need. The `TagsController#list`
action added here is also much safer since the response is paginated and
we avoid loading a whole bunch of tags upfront.
Why this change?
A new component based API for modals was introduced in
b3a23bd9d6. This commit moves the edit
navigation menu tags and categories modal to the new API.
