[BUG]: Ensure that implicit conversions for `begin_bit`/`end_bit` don't break radix sort APIs.

### Is this a duplicate?

- [X] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this bug and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Type of Bug

Compile-time Error

### Component

CUB

### Describe the bug

The radix sort decomposer APIs may break implicit conversions for the `begin_bit`/`end_bit` APIs, and will require some SFINAE logic to ensure that overloads are selected correctly.

The old non-catch2 radix sort test contains the snippet in the first comment, which was permanently disabled until the SFINAE logic was sorted out. We can port this test to catch2 once the APIs are fixed.