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/mod.rs

@@ -51,7 +51,7 @@ pub fn parse_tokens(mut tokens: TokenStream) -> ParseResult {
         } else {
             format!("found unknown tokens [{}]", token_list.join(", "))
         };
-        return KclError::Lexical(KclErrorDetails::new(message, source_ranges)).into();
+        return KclError::new_lexical(KclErrorDetails::new(message, source_ranges)).into();
     }
 
     // Important, to not call this before the unknown tokens check.
@@ -110,7 +110,7 @@ impl ParseResult {
         let (p, errs) = self.0?;
 
         if let Some(err) = errs.iter().find(|e| e.severity.is_err()) {
-            return Err(KclError::Syntax(err.clone().into()));
+            return Err(KclError::new_syntax(err.clone().into()));
         }
         match p {
             Some(p) => Ok(p),

rust/kcl-lib/src/parsing/parser.rs

@@ -4412,7 +4412,7 @@ secondExtrude = startSketchOn(XY)
     #[test]
     fn test_parse_parens_unicode() {
         let result = crate::parsing::top_level_parse("(ޜ");
-        let KclError::Lexical(details) = result.0.unwrap_err() else {
+        let KclError::Lexical { details } = result.0.unwrap_err() else {
             panic!();
         };
         // TODO: Better errors when program cannot tokenize.

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)],
         ))