gts indent doesn't match Google style

Specifically when breaking lines. Google style has good line break rules that prettier's indent rules conflicts with. Given that `gts` enforces `prettier/prettier`, my fix gives me breaks like this:

```typescript
new Error('This is a long string that we'll need to break. Google style'
+ 'recommends continuing at at least +4 spaces, while prettier enforces +2');
```

Here's the corresponding rule: https://google.github.io/styleguide/jsguide.html#formatting-indent