RFC: Rename CuArrays.CURAND.curand -> CuArrays.CURAND.rand

[mohamed82008]

Following up on a discussion on Slack, I suggest that CuArrays should have its own rand function different from Base.rand. To avoid namespace confusion though, CuArrays.rand should not be exported. A PR is somewhat straight-forward, but I am opening an issue first to get some opinions.

[maleadt]

@MikeInnes @vchuravy @kshyatt @andreasnoack

I was initially opposed, thinking it could be confusing and we should export curand instead, but that's pretty similar to CuArrays.rand. Besides, we've been doing this anyway for eg. CUDAnative.sin.

Note that in the long term we should be moving towards CuArray{T}(rand, dims), but that would need some design consideration and isn't as straightforward (eg. how to implement rand(1:2, 3)).

[MikeInnes]

CuArrays.rand seems fine to me. CuArray{T}(rand, ...) seems kind of backwards to me but I guess it's not that inconsistent with undef; though it seems stranger for things like fill. rand(CuArray, ...) is another option that has some precedent with similar.