zink: handle scissor+viewport states dynamically if extension is available

zink: handle scissor+viewport states dynamically if extension is available

this is a huge perf win since it means we don't have to create a new pipeline
every time this state changes

also we can now move the viewport state back to zink_context since that's the
real value we're using and the pipeline state value is just for the hash

ref mesa/mesa#3359

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9153>