Insert empty line between suite and alternative branch after def/class (#12294)

When there is a function or class definition at the end of a suite
followed by the beginning of an alternative block, we have to insert a
single empty line between them.

In the if-else-statement example below, we insert an empty line after
the `foo` in the if-block, but none after the else-block `foo`, since in
the latter case the enclosing suite already adds empty lines.

```python
if sys.version_info >= (3, 10):
    def foo():
        return "new"
else:
    def foo():
        return "old"
class Bar:
    pass
```

To do so, we track whether the current suite is the last one in the
current statement with a new option on the suite kind.

Fixes #12199

---------

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_python_formatter/src/statement/stmt_with.rs

@@ -14,6 +14,7 @@ use crate::other::commas;
 use crate::other::with_item::WithItemLayout;
 use crate::prelude::*;
 use crate::statement::clause::{clause_body, clause_header, ClauseHeader};
+use crate::statement::suite::SuiteKind;
 use crate::PythonVersion;
 
 #[derive(Default)]
@@ -124,7 +125,7 @@ impl FormatNodeRule<StmtWith> for FormatStmtWith {
                         }
                     })
                 ),
-                clause_body(&with_stmt.body, colon_comments)
+                clause_body(&with_stmt.body, SuiteKind::other(true), colon_comments)
             ]
         )
     }