Add example implementing filter pushdown

[alamb]

Is your feature request related to a problem or challenge?

@pgwhalen says on https://github.com/apache/datafusion-site/pull/161/changes#r2972139725

As someone who struggled with implementing filter pushdown in a custom table provider before, it would be helpful if there was a section with examples on actually implementing it, just to specifying that the table provider supports it. Going from filters: &[Expr] to something more useful was pretty intimidating for me as a newbie. I ended up learning about LiteralGuarantee::analyze from the pruning_predicate.rs example and that was the big unlock, but as someone not familiar with database internals terminology, it was nonobvious initially.

Describe the solution you'd like

It would be cool to add an example that shows how to use PruningPredicate and LiteralGuarantee to decide among files based on predicates, for example

Describe alternatives you've considered

No response

Additional context

No response

[alamb]

Somewhere in https://github.com/apache/datafusion/tree/main/datafusion-examples/examples/custom_data_source I think would be good

[alamb]

Note the example on apache/datafusion-site#161 shows the setup needed, but the idea of this example would be to show how to use pruning prediate / gaurantees to actually implement the filtering