Adds the plumbing to start making RM control calls, and initialises
objects to represent internal RM objects provided to us during init.

These will be used by subsequent patches.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230918202149.4343-34-skeggsb@gmail.com