[BUG] IVF-PQ build / extend API does not support host mdspan

[tfeher]

The pointer based APIs in RAFT for ivf_pq::build and ivf_pq::extend do accept host and device arrays (as well es pinned, and managed arrays). Accepting host arrays is an important feature: IVF-PQ algorithm allows us to build index from dataset that is larger than GPU memory (it can be even larger than host memory, if the data is mmap-ed). The cuVS interface should also support host arrays.