[FEA] Rename PascalCase types introduced by the rapidsmpf migration to snake_case

**Is your feature request related to a problem? Please describe.**
#22747 migrates rapidsmpf code into libcudf (the new `libcudf_streaming` library). Some of the migrated types came over with `PascalCase` names that do not follow libcudf's naming convention.

**Describe the solution you'd like**
Per the Developer Guide (https://github.com/rapidsai/cudf/blob/HEAD/cpp/doxygen/developer_guide/DEVELOPER_GUIDE.md#code-and-documentation-style-and-formatting): "libcudf code uses snake_case for all
names except in a few cases: template parameters, unit tests and test case names may use Pascal case." Classes are not an exception.

Rename, e.g. `HashScheme` and `BloomFilter` (and audit the rest of the migrated `libcudf_streaming` code for other PascalCase classes/functions/enums) to `hash_scheme` and `bloom_filter` so the new library matches libcudf conventions.