Resolves: #i123895# split impfont.cxx source from metric.cxx

and move the helper function UpdateAttributesFromPSName() there to
make it available for all platforms, not only ATSUI-based ones.

(cherry picked from commit a3895516f02a80151caaac8b92fb50aa5f7ee93b)

Conflicts:
	include/vcl/metric.hxx
	vcl/aqua/source/gdi/salatsuifontutils.cxx
	vcl/inc/impfont.hxx
	vcl/source/gdi/metric.cxx

Change-Id: I6d5702d429673c83740cb72775014f8942e5f44d