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.
e29ee9d1ca