pan/bi: Add swizzles

Requires a new field on bifrost_instruction, as well as a new class
property and a new class for the dedicated swizzle ops.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4061>
2 files changed