[BUG] libcudf tests of binary operations (in `binop-compiled-test.cpp`) mostly do not test against a ground truth

**Describe the bug**

Binary operations between columns are implemented by runtime typed dispatch to device functors in [`cpp/src/binaryop/compiled/operation.cuh`](https://github.com/rapidsai/cudf/blob/7426a06a4510280650df4cf54b76504d690c80b2/cpp/src/binaryop/compiled/operation.cuh).

Tests of this functionality compare to host-based compute, with an implementation of the functors in [`cpp/tests/binaryop/util/operation.h`](https://github.com/rapidsai/cudf/blob/7426a06a4510280650df4cf54b76504d690c80b2/cpp/tests/binaryop/util/operation.h)

This is a very weak test of correctness that really is testing:

1. Can the author of the test copy the device functor implementation into the host implementation?
2. Can the device and host compilers emit correct code for these cases?

These tests should more properly test against a ground truth (either manually constructed, or automatically).