doc comment forces multiline exceptions

1. type `exception Foo({name: string, msg: string})` and run formatter
2. notice still single line
3. add doc comment:
```
/** foo */
exception Foo({name: string, msg: string})
```
and run formatter
4. notice how formatter forces multiline:
```
/** foo */
exception Foo({
  name: string,
  msg: string,
})

```

see also #7946 