Is your feature request related to a problem or challenge? Please describe what you are trying to do.

The arrow::util::data_gen module provides a create_random_array for generating random arrays for various data types.
However, it does not support Decimal data type yet. And an error would occur if we were tried to call it on a Decimal data type:

called `Result::unwrap()` on an `Err` value: NotYetImplemented("Generating random arrays not yet implemented for Decimal128(15, 2)")

Describe the solution you'd like

Support random generation for decimal data types.

Describe alternatives you've considered

Additional context