[EPIC] (Even More) Grouping / Group By / Aggregation Performance

### Is your feature request related to a problem or challenge?

Aggregation is a key operation of Analytic engines. DataFusion has made great progress recently (e.g. https://github.com/apache/arrow-datafusion/issues/4973 and https://github.com/apache/arrow-datafusion/issues/6889)

This Epic gathers other potential ways we can improve the performance of aggregation

Core Hash Grouping Algorithm:
- [x] https://github.com/apache/arrow-datafusion/issues/6969
- [x] https://github.com/apache/arrow-datafusion/issues/7064
- [x] https://github.com/apache/arrow-datafusion/issues/9403
- [x] https://github.com/apache/arrow-datafusion/issues/7023
- [x] https://github.com/apache/arrow-datafusion/issues/7095

Specialized Aggregators:
- [x] https://github.com/apache/arrow-datafusion/issues/6906
- [x] https://github.com/apache/arrow-datafusion/issues/5547
- [x] https://github.com/apache/arrow-datafusion/issues/5472
- [ ] https://github.com/apache/arrow-datafusion/issues/7065
- [ ] https://github.com/apache/arrow-datafusion/issues/7066

New features:
- [x] https://github.com/apache/arrow-datafusion/issues/6937
- [ ] https://github.com/apache/arrow-datafusion/issues/9562
- [ ] https://github.com/apache/arrow-datafusion/issues/8699
- [x] https://github.com/apache/arrow-datafusion/issues/8934

Improved partitioning:
- [ ] https://github.com/apache/arrow-datafusion/issues/6928
- [ ] https://github.com/apache/arrow-datafusion/issues/7001
- [ ] https://github.com/apache/arrow-datafusion/issues/6822

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

The payload names no files, tests, or entry points. Start by opening the unchecked linked issues 7065, 7066, 9562, 8699, 6928, 7001, and 6822; completion must follow the selected issue's scope and acceptance criteria rather than this umbrella epic.

Written by the indexing model from the issue text.