Replace some AphrontView::setUser() calls with AphrontView::setViewer()
Summary:
See rPaaab1011e5a464ea94c182001a7fe867b19bae5a.
`AphrontView::setUser()` is deprecated.
Save a few CPU cycles and nuclear power plants.
Test Plan:
Read the code.
Even better, intentionally introduce an error in `AphrontView::setUser()`
and browse random Phorge pages and then replace the call accordingly (as
there are numerous `setUser()` methods across the codebase and we don't
want no explosions).
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D25880