Lexer start of line is false only for Mode::Expression (#8880)

## Summary

This PR fixes the bug in the lexer where the `Mode::Ipython` wasn't
being considered when initializing the soft keyword transformer which
wraps the lexer. This means that if the source code starts with either
`match` or `type` keyword, then the keywords were being considered as
name tokens instead. For example,

```python
match foo:
    case bar:
        pass
```

This would transform the `match` keyword into an identifier if the mode
is `Ipython`.

The fix is to reverse the condition in the soft keyword initializer so
that any new modes are by default considered as the lexer being at start
of line.

## Test Plan

Add a new test case for `Mode::Ipython` and verify the snapshot.

fixes: #8870

crates/ruff_python_parser/src/lexer.rs

@@ -2160,6 +2160,14 @@ f"{(lambda x:{x})}"
         assert_debug_snapshot!(lex_source(source));
     }
 
+    #[test]
+    fn test_match_softkeyword_in_notebook() {
+        let source = r"match foo:
+    case bar:
+        pass";
+        assert_debug_snapshot!(lex_jupyter_source(source));
+    }
+
     fn lex_fstring_error(source: &str) -> FStringErrorType {
         match lex(source, Mode::Module).find_map(std::result::Result::err) {
             Some(err) => match err.error {