The DrawControlText always renders with a reference device positions but
we pass in a rectangle which is derived a different way.

So, add a GetControlTextRect which operates on the same reference
device as DrawControlText so the rectangles match

The rectangle is mapped from pixels to logic and back from logic
to pixel, so add an argument to store the logic size from
GetControlTextRect and re-use it without conversion on the cases
where we pass back the original rectangle

zooming in/out on the button in writer is now stable wrt text shown at all zoom
levels

Change-Id: Ic581eca67d0ff265e2753ab8b6c40e8fca7e6ae4
Reviewed-on: https://gerrit.libreoffice.org/33277Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>