[FEA] Improve libcudf hashing tests

**Is your feature request related to a problem? Please describe.**
Currently the hashing tests use a relatively small number of fixed values and some tests should be parameterized to test all possible input types.

**Describe the solution you'd like**
Ideally the tests should use procedurally generated input with the ability to generate a controllable percentage of nulls and corner case values (e.g.: min/max values, zero, -0.0/NaN,+/-Inf for floating point types, etc.). The results should then be compared against a reference CPU implementation that computes on the same input.

There should also be negative tests that verify any unsupported input types throw appropriate exceptions.