[FEA][JNI] Move to RMM apis get_current_device_resource_ref and set_current_device_resource_ref

This change https://github.com/rapidsai/rmm/pull/1661 deprecates the pointer based `get_current_device_resource` and `set_current_device_resource` in favor of a non-owning reference based `set_current_device_resource_ref` and `get_current_device_resource_ref`.

RMM JNI currently uses the pointer based apis so we want to move to the new `_ref` versions. I don't think we need to worry about ownership, because we already have a java object tracking a heap allocated memory resource.