[DRAFT][SPARK-47690][SQL] Hash aggregate support for strings with collation

[uros-db]

What changes were proposed in this pull request?

Enable collation support for hash aggregate.

Why are the changes needed?

Improve AGGREGATE performance for collated strings, arrays of strings, and structs with strings.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

E2e SQL tests in CollationSuite, existing TPCDS collation query test suite.

Was this patch authored or co-authored using generative AI tooling?

Yes.