[EPIC]: Make `PiecewiseMergeJoin` work in Datafusion

[jonathanc-n]

Is your feature request related to a problem or challenge?

I will organize the following tasks that will be done in separate pull requests as #16660 got a little large and confusing.

The following is to be done roughly in order:

• feat: ClassicJoin for PWMJ #17482
• Add existence join support (in another file) + fuzz tests
• Mark join support
• Serialization

The classic join and existence join will have their own stream implementation as the logic is completely different. Nice little suggestion from @2010YOUY01 😄

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

No response

[jonathanc-n]

This should be quite straightforward since the code is already done. Hopefully we can get started on IE joins after this

[jonathanc-n]

take