pan/bi: Track clause types during scheduling

pan/bi: Track clause types during scheduling

There's an easy mapping for this, so let's do it. Note we do this at
schedule-time instead of emit since we'll need to lookahead clause
types. The alternative is a prepass running after schedule but before
codegen, but there's no reason not to just stick it here when we're
preparing bi_clause in the first place.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4242>