panvk: add support for adjacency primitive topologies

These are not usable by applications until we advertise GS, but the
implementation is effectively independent of the rest of the GS
implementation.

Signed-off-by: Olivia Lee <olivia.lee@collabora.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Lars-Ivar Hesselberg Simonsen <lars-ivar.simonsen@arm.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41478>