[C++][Python] Unifying differing dictionaries in Arrow compute

### Describe the bug, including details regarding any error messages, version, and platform.

I received the above error when trying to run group_by() with a key column defined as dictionary

Also tried dictionary but received the same error.

When I changed the key column to string(), group_by() ran successfully.

I am therefore guessing that key columns of datatype dictionary are currently not supported by group_by().

Is group_by() support for dictionary key columns planned?

Current setup is :

Windows 11
Python 3.10
pyarrow 10.0.1

### Component(s)

Python

Start by reproducing group_by() with a dictionary key column using the reported Windows 11, Python 3.10, and pyarrow 10.0.1 setup, then trace the Arrow compute group_by path for dictionary handling. Done means dictionary key columns, including differing ordered states, are supported without the reported error and the behavior is covered by relevant tests.

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