Improve documentation and add examples for ArrowPredicateFn

[alamb]

Which issue does this PR close?

• Part of arrow_reader_row_filter benchmark doesn't capture page cache improvements #7460

Rationale for this change

• While working on Add arrow_reader_clickbench benchmark #7470 it took me some time to work out how to use ArrowPredicateFn. I would like to make it easier for my future self. I also plan to publicize this API more over the next few months so having clear documentation is a good thing

What changes are included in this PR?

Improve documentation and add examples for ArrowPredicateFn

Are there any user-facing changes?

Documentation only, no functional changes

[phillipleblanc]

Thanks for working on this! I happened to run into ArrowPredicateFn while working on an issue in the iceberg-rust crate, and this is helpful for understanding it.

[alamb]

Thank you for the review @phillipleblanc