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GH-33484: [C++][Compute] Implement `Grouper::Reset` (#41352)



### Rationale for this change

Recently I've been working on some improvement for `Grouper` and I found adding `Reset` function could be beneficial. Then I trace down to #33484 from a TODO in code. Here comes this PR.

### What changes are included in this PR?

Add `Reset` function for all the concrete `Grouper` implementations, and eliminate the recreation of `Grouper` in `AnyKeysSegmenter`.

Also add more `RowSegmenter` cases covering `AnyKeysSegmenter`.

### Are these changes tested?

Yes. Legacy UTs should cover it well. Also added some new UTs.

### Are there any user-facing changes?

None.

* GitHub Issue: #33484

Lead-authored-by: Ruoxi Sun <zanmato1984@gmail.com>
Co-authored-by: Rossi Sun <zanmato1984@gmail.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Signed-off-by: Antoine Pitrou <antoine@python.org>