Migrate favorites to bbPress 2.x

[SergeyBiryukov]

One of our moderators noted that favorited topics were not migrated to the new forums.

As noted in the ​July 28th meeting transcript, they can be transferred, but there's no place for them in the profile:

Subscriptions are coming with; user roles for moderators are also getting ported. Favorites are not, they can be backfilled pretty easily, but there is no place to actually view them on a current user profile.

So let's find a way to display favorites in user profile and bring them back.

[jmdodd]

All favorites have been migrated for existing bbPress 2 Rosetta forums. This still doesn't solve the display issue, but they are accessible at:
​https://ru.wordpress.org/support/users/ ... your username ... /favorites/

[SergeyBiryukov]

With the profile issue resolved in #1868, I think comment:2 resolves this ticket.