Add native comparison kernel support for DictionaryArray

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Today, DataFusion's expression evaluation does not work natively on DictionaryArrays; Instead what happens is that the DictionaryArrays are unpacked into their base type (e.g. a string dictionary gets unpacked into a StringArray)

This is very inefficient, especially for expressions like col != 'foo' -- if col is a DictionaryArray this filter could be applied by finding 'foo' in the dictionary and then checking for values with that dictionary index, and the dictionary could be reused at the output.

Describe the solution you'd like

1. Add kernels that can compare DictionaryArrays (eq_dict, lt_dict, etc)
2. Add DataType::Dictionary to the the eq_dyn and the other dynamic kernels implemented in implement eq_dyn, neq_dyn, lt_dyn, lt_eq_dyn, gt_dyn, gt_eq_dyn #858

Describe alternatives you've considered
N/A

Additional context

[matthewmturner]

@alamb im interested in taking this. will start looking into it.

[alamb]

sounds great @matthewmturner -- thank you!

[alamb]

I think we have a proposed interface in #1074

[alamb]

I believe this task is now complete. Thanks again @matthewmturner

[matthewmturner]

I believe this task is now complete. Thanks again @matthewmturner

Thanks for patience and guidance @alamb :)