Use arrow row format in GroupByHash rather than datafusion row format #4179

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Arrow now has a row format https://docs.rs/arrow/26.0.0/arrow/row/index.html that is both well documented and likely to get additional functionality (as it will be used for sorting, etc)

It would be good to use that in DataFusion to benefit from upstream efforts including more type support as it is added

Describe the solution you'd like
It would be great to use the Arrow row format instead of Compact layout: https://github.com/apache/arrow-datafusion/blob/f2f846512ab032845de5dcee768a8a69ddf17eac/datafusion/row/src/layout.rs#L68

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
As part of #3940 and #3941 I believe @crepererum is working on this feature

cc @yjshen and @tustvold