BUG: Patch rank() uint64 behavior

Adds `uint64` ranking functions to `algos.pyx` to allow for proper
ranking with `uint64`.    Also introduces partial patch for
`factorize()` by adding `uint64` hashtables and vectors for  usage.
However, this patch is only partial because the larger bug of non-
support for `uint64`  in `Index` has not been fixed (**UPDATE**:
tackled in #14937):  ~~~python  >>> from pandas import Index, np  >>>
Index(np.array([2**63], dtype=np.uint64))
Int64Index([-9223372036854775808], dtype='int64')  ~~~    Also patches
a bug in `UInt64HashTable` from #14915 that had an erroneous null
condition that was caught during testing and was hence removed.

Author: gfyoung <[email protected]>

Closes #14935 from gfyoung/core-algorithms-uint64-two and squashes the following commits:

2598cea [gfyoung] BUG: Patch rank() uint64 behavior

Author: gfyoung