Lift named remap functions out of the parser

[JeanMertz]

Right now our parser explicitly lists the function names that are supported, this means each new function needs to be added to that list.

Ideally the parser knows how to parse a generic function signature, which we can then map to a Rust enum to match the specific function. This reduces boilerplate, and in general is a good practice to follow.

See:

• feat(new transform): New remap transform #3341 (comment)
• feat(remap transform): Add new set of functions #3767 (comment)