[Data] support batch_format for Sort and Aggregate

[xingyu-long]

Why are these changes needed?

While we calling xxx.map_groups(..., batch_format="..."), we may invoke sort function and creating empty blocks which still uses pyarrow by default. And, when we invoke another sort call on top of it, we will hit AttributeError: 'DataFrame' object has no attribute 'num_rows' since we uses first block type. (However, we may have different blocks). See more details in #46748

Related issue number

Close #46748

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[xingyu-long]

Hi @scottjlee, could you take a look when you have time? Thanks a lot!

[scottjlee]

Great start, have a suggestion on how we can set the batch_format without having it explicitly set at Dataset level.

[scottjlee]

Thanks for your contribution @xingyu-long !