Deprecates all cases where `Link` could be sent as a prop. This was a
relic from the past, where we attempted to make our UI library
router-agnostic. This was a pipe dream and created more problems than it
solved, for example the logout button was missing this prop, causing it
to render an anchor tag and perform a hard navigation (caught in #9275).
Does so in a non-breaking way, where these props are now optional and
simply unused, as opposed to removing them outright.
cd1117515b