This refactors and fixes unicode issues where entities don't display
properly due to being a special character that seems to be rendered
incorrectly in a non-deterministic way every time.
This either removes aria-hidden=true assignments from buttons with
text, or adds a span to only hide the 'x' symbol rather than the
button for closing buttons.
Our current workflow for creating a new stream allows the user to
invite as many other users as they like but since there can be
mistakes in doing so, we now open a modal with a warning if the
number of invites are more than 100 just to confirm that user indeed
wanted to do this.
Fixes: #1663.