Move libcudf reduction google-benchmarks to nvbench

[davidwendt]

Description

Reworks the reduction benchmarks currently coded with google-bench to use nvbench instead.
This removes the need to support row_bit_count for dictionary column types.
#16121

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[davidwendt]

/merge