Fix multiranges to behave more like dependent types.

Fix multiranges to behave more like dependent types.

For most purposes, multiranges act like dependent objects of the
associated range type: you can't create them separately or drop them
separately.  This is like the way that autogenerated array types
behave.  However, a couple of points were overlooked: array types
automatically track the ownership of their base type, and array types
do not have their own permissions but use those of the base type,
while multiranges didn't emulate those behaviors.  This is fairly
broken, mainly because pg_dump doesn't think it needs to worry about
multiranges as separate objects, and thus it fails to dump/restore
ownership or permissions of multiranges.

There's no apparent value in letting a multirange diverge from
its parent's ownership or permissions, so let's make them act like
arrays in these respects.  However, we continue to let multiranges
be renamed or moved to a different schema independently of their
parent, since that doesn't break anything.

Discussion: https://postgr.es/m/1580383.1705343264@sss.pgh.pa.us