Add test for ClipToPicture

This draws a rect clipped by a text, and a text clipped by a rect. They
should look the same, but they don't because of lack of antialiasing
support in ClipToPicture.
BView: move ClipToPicture code to app_server

Now that DrawingContext makes it possible to draw on a ServerBitmap
without the need for a BView, we can replay pictures on app_server side,
avoiding the cost of creating a BBitmap, offscreen BWindow, and BView
from the application side.

The offscreen drawing context gets the same state as the view it's
rendering the picture for, so font size, drawing mode, etc are used.

The implementation is still the suboptimal one, converting the BBitmap
to a BRegion, and using that for clipping. Changing that comes next.
Drop --remote-user configuration option again.

* as Ingo has pointed out, the remote user settings doesn't
  relate to the build configuration at all, so setting the
  remote user via HAIKU_REMOTE_USER in UserBuildConfig or
  via shell environment is the way to go
* additionally: drop debug output