509 Regression: `@available` with multiline string literal produces code that doesn't compile

```
$ swift-format
@available(
  iOS,
  deprecated: 9999,
  message:    
    """
    Deprecated.

    See https://more.info
    """
)
func f() {}
```
```
@available(
  iOS,
  deprecated: 9999,
  message: """Deprecated. 🛑

  See https://more.info"""
)
func f() {}
```

> 🛑 Multi-line string literal content must begin on a new line