WIP: Interpreted MFP evaluation

[antiguru]

Only trampoline once!

This adds an alternative evaluation mode for scalar expressions. At the moment, we evaluate expressions by matching on big enums. This form of evaluation is slow and does a lot of repeated work on every invocation.

Instead, we remember a function pointer paired with parameters and call the function directly. While it still comes with an overhead because the function is a separate function, we skip the function enum matching.

Signed-off-by: Moritz Hoffmann mh@materialize.com

Motivation

Tips for reviewer

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered. (trigger-ci for additional test/nightly runs)
• This PR has an associated up-to-date design doc, is a design doc (template), or is sufficiently small to not require a design.
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