KCL: Use named fields for KclError (#7321)

We've changed the unnamed field of `KclError` variants to a named called `details`.

To clarify: previously KCL errors looked like this:

```rust
pub enum KclError {
    Lexical(KclErrorDetails),
    Syntax(KclErrorDetails),
```

Now they look like this:

```rust
pub enum KclError {
    Lexical { details: KclErrorDetails },
    Syntax { details: KclErrorDetails },
}
```

This lets us more easily add fields to the errors. For example, in the UndefinedValue case, adding a field for what the undefined name was. This PR refactors the code to make my PR in https://github.com/KittyCAD/modeling-app/pull/7309 much easier.

Pure refactor, should not change any behaviour.

rust/kcl-lib/src/std/math.rs

@@ -56,7 +56,7 @@ pub async fn sqrt(exec_state: &mut ExecState, args: Args) -> Result<KclValue, Kc
     let input: TyF64 = args.get_unlabeled_kw_arg_typed("input", &RuntimeType::num_any(), exec_state)?;
 
     if input.n < 0.0 {
-        return Err(KclError::Semantic(KclErrorDetails::new(
+        return Err(KclError::new_semantic(KclErrorDetails::new(
             format!(
                 "Attempt to take square root (`sqrt`) of a number less than zero ({})",
                 input.n