nav: Make each user's avatar in group-PM app bar lead to profile.
nav: Make each user's avatar in group-PM app bar lead to profile.

Parallel to the similar change for 1:1 PMs in the parent commit.
This again is a natural thing to try, and this seems pretty solidly
the best thing for it to do if it does something.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile