tsgo breaks type soundness for lone-surrogate string literals

## Steps to reproduce

```ts
const x: "\uD800" = "\uDC00";
```

## Behavior with `typescript@6.0`

```
bug.ts:1:7 - error TS2322: Type '"\uDC00"' is not assignable to type '"\uD800"'.

1 const x: "\uD800" = "\uDC00";
        ~
```

## Behavior with `tsgo`

Typechecks (but shouldn't).