Isolated declarations quick fix explicitly prints out default type arguments

```ts
// @declaration: true
// @isolatedDeclarations: true

export interface Foo<T, U = T[]> {
}

export function /**/foo(x: Foo<string>) {
    return x;
}
```

Request a quick fix at `/**/`.

**Current**:

```
Add return type 'Foo<string, string[]>'.
```

**Expected**:

```
Add return type 'Foo<string>'.
```