This adds tabindex='0' in anchor tags for allowing the message menu
popover box to be focusable using hotkey 'i' through keyboard.
This is a necessary follow up to
729c09074a, which removed the href
attribute from anchor tags to which click-handlers were attached,
which resulted in making them non-focusable as jQuery doesn't allow
anchor tags to be focusable without tab-index or href attribute.
Fixes#21125.
As seen in
https://chat.zulip.org/#narrow/stream/9-issues/topic/edit.20history.20bug/near/1320430,
clicking such a link takes you to the user's default view if the click
handler throws an exception before doing preventDefault().
There hrefs also have the negative effect of having your browser claim
that clicking the link will navigate you to the default view, which it
won't.
Comes with a linter rule to prevent future instances, since it seems
there are some recently added ones, though they are likely the result
of copy/paste.
jai2201
Tim Abbott
Anders Kaseorg