All KCL types should have human-friendly types

[adamchalmers]

Right now KCL types have names taken from Rust. E.g. SketchOrSurface's type is defined in Rust, and its name is the name of the Rust type.

But we should allow KCL types to present different names to KCL users. For example, when KCL gives a type error it shouldn't say "Expected SketchOrSurface". Rather, the error should say "Expected either a Sketch or a Surface".

Possible implementation

Add a new method to trait FromKclValue, something like fn type_name() -> String. Then use that in error messages. It could have a default implementation which calls to tynm::type_name or something, and then for some types we could override it.