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/parsing/token/mod.rs

@@ -597,7 +597,7 @@ impl From<ParseError<Input<'_>, winnow::error::ContextError>> for KclError {
             // This is an offset, not an index, and may point to
             // the end of input (input.len()) on eof errors.
 
-            return KclError::Lexical(crate::errors::KclErrorDetails::new(
+            return KclError::new_lexical(crate::errors::KclErrorDetails::new(
                 "unexpected EOF while parsing".to_owned(),
                 vec![SourceRange::new(offset, offset, module_id)],
             ));
@@ -608,7 +608,7 @@ impl From<ParseError<Input<'_>, winnow::error::ContextError>> for KclError {
         let bad_token = &input[offset];
         // TODO: Add the Winnow parser context to the error.
         // See https://github.com/KittyCAD/modeling-app/issues/784
-        KclError::Lexical(crate::errors::KclErrorDetails::new(
+        KclError::new_lexical(crate::errors::KclErrorDetails::new(
             format!("found unknown token '{}'", bad_token),
             vec![SourceRange::new(offset, offset + 1, module_id)],
         ))