wined3d: Ask the ffp/shader/blit implementation about format support.

wined3d: Ask the ffp/shader/blit implementation about format support.

If a format is not supported natively by opengl, a shader may be able
to convert it. Up to now, CheckDeviceFormat had magic knowldge which
GL extensions lead to which supported format. This patch adds
functions that allow CheckDeviceFormat to ask the actual
implementation for its capabilities.