asahi,hk: significantly rework GS

get rid of the rasterizer discard variants, by pushing XFB into the hardware VS
and letting everything cascade down from there. that then means hardware VS runs
for all streams, which means we get dynamic rasterization stream selection.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35802>
13 files changed