Store any_resource in device_uvector_policy

[bdice]

Part of https://github.com/rapidsai/rmm/issues/2011.

Depends on https://github.com/rapidsai/rmm/pull/2200.

Change device_uvector_policy::mr_ from device_async_resource_ref to cuda::mr::any_resource<cuda::mr::device_accessible>.

This ensures the container policy owns its memory resource, preventing use-after-free if the original resource is destroyed while the policy still exists.