Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Once #2639 is merged we should add support for serializing plans that contain subquery expressions.

This will likely require breaking changes to the API because we currently have one API for Expr that optionally accepts a FunctionRegistry and one API for LogicalPlan that optionally accepts a LogicalExtensionCodec. With subquery support we have plans referencing expressions and expressions referencing plans, so these APIs will need to be combined somehow.

Here is a suggestion for the new API from the discussion at #2639 (comment)

let bytes = PlanSerializer::new()
    .with_extension_codec(&extension_codec)
   .serialize()?;

Describe the solution you'd like
TBD

Describe alternatives you've considered
None

Additional context
None