Null aware hash mark joins

[AdamGS]

This is still a draft, I'm putting it up because because might want to weigh in, and I find it useful to be able to see the diff clearly.

Which issue does this PR close?

• Closes Mark joins don't support null mark columns #21309.

Rationale for this change

This change is about correctness/sql completeness, but is also a step towards better subquery de-correlation.

What changes are included in this PR?

1. Adds support for null-aware mark joins
2. Make sure queries that joins that require null awareness go through a join implementation that supports that.

Are these changes tested?

1. Existing SLT tests that explicitly showed bad results.
2. New dedicated SLT tests.
3. New unit tests.

Are there any user-facing changes?

This PR changes planning behavior and introduces more public API around hash joins, I'll finalize this section as it gets closer to a reviewable state.

AI Usage

AI was used in the process of developing this PR, mostly around testing and planning