[BUG] RNG API fixes

[MatthiasKohl]

After merging PR #609 , I realized that there were still a few bugs (all minor):

1. The deprecated Rng class had the type attribute removed. I added it back. This was used in cugraph-ops but not in other projects (cugraph, cuml).
2. The template function to call another function with the device state was actually unusable since you wouldn't be able to instantiate a function to call it with. So I removed that.
3. The macro used to call functions with a device state wasn't using fully namespace-qualified names, which made it unusable outside of RAFT.
4. Removed the deprecation warning of the new rng_device.cuh since it has to be included anyway through rng.cuh, so those deprecations didn't make sense.

[MatthiasKohl]

rerun tests

[MatthiasKohl]

rerun tests

[cjnolet]

@gpucibot merge