[Rust] [DataFusion] Support GROUP BY for Dictionary columns

[asfimport]

If you try and run a query that groups on a column encoded as a Dictionary you get an error about "unsupported GROUP BY type". You should get the same result as if your data was encoded using a primitive array type.

Reporter: Andrew Lamb / @alamb
Assignee: Andrew Lamb / @alamb

PRs and other links:

• GitHub Pull Request #9233

_{Note: This issue was originally created as ARROW-11289. Please see the migration documentation for further details.}

[asfimport]

Andrew Lamb / @alamb:
Issue resolved by pull request 9233
#9233