Fix D204 when there's a semicolon after a docstring (#7174)

## Summary

Another statement on the same line as the docstring would previous make
the D204 (newline after docstring) fix fail:

```python
class StatementOnSameLineAsDocstring:
    "After this docstring there's another statement on the same line separated by a semicolon." ;priorities=1
    def sort_services(self):
        pass
```

The fix handles this case manually:

```python
class StatementOnSameLineAsDocstring:
    "After this docstring there's another statement on the same line separated by a semicolon."

    priorities=1
    def sort_services(self):
        pass
```

Fixes #7088

## Test Plan

Added a new `D` test case

crates/ruff_source_file/src/newlines.rs

@@ -32,6 +32,7 @@ impl UniversalNewlines for str {
 /// assert_eq!(lines.next_back(), Some(Line::new("\r\n", TextSize::from(8))));
 /// assert_eq!(lines.next(), None);
 /// ```
+#[derive(Clone)]
 pub struct UniversalNewlineIterator<'a> {
     text: &'a str,
     offset: TextSize,