lavapipe: add a mapping for BDA

lavapipe: add a mapping for BDA

when passing around BDA, it's important to be able to link the pointer
back to the pipe_resource since BDA doesn't have an explicit lifetime

this mapping enables cmds to receive a BDA pointer and then map it back
to a pipe_resource in order to avoid gymnastics with dynamically creating
pipe_resource objects which may or may not be able to be freed

Acked-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23394>