[IMP] website_slides: Add course tags creation to frontend

This commit makes it possible for course tags to be added via the
frontend. To support this, course tags were also made viewable in a
specific course's website since previously these tags were only visible
in the courses frontpage (i.e. within the course cards). "Add Tag" is
placed after course page's tags. Note that due to the ability to make new
tags within this "Add Tag" modal restricts addition to only 1 tag at a
time since new tags require a "Tap Group" to be assigned and handling a
mix of new/existing tags would get confusing and complicated.

Supports Task: 2128166
PR #44365