Move flake8-executable rules out of physical lines checker (#6039)

## Summary

These only need the token stream, and we always prefer token-based to
physical line-based rules.

There are a few other changes snuck in here:

- Renaming the rule files to match the diagnostic names (likely an
error).
- The "leading whitespace before shebang" rule now works regardless of
where the comment occurs (i.e., if the shebang is on the second line,
and the first line is blank, we flag and remove that leading
whitespace).

crates/ruff/src/comments/shebang.rs

@@ -1,15 +1,10 @@
-use ruff_python_trivia::{is_python_whitespace, Cursor};
-use ruff_text_size::{TextLen, TextSize};
+use std::ops::Deref;
+
+use ruff_python_trivia::Cursor;
 
 /// A shebang directive (e.g., `#!/usr/bin/env python3`).
 #[derive(Debug, PartialEq, Eq)]
-pub(crate) struct ShebangDirective<'a> {
-    /// The offset of the directive contents (e.g., `/usr/bin/env python3`) from the start of the
-    /// line.
-    pub(crate) offset: TextSize,
-    /// The contents of the directive (e.g., `"/usr/bin/env python3"`).
-    pub(crate) contents: &'a str,
-}
+pub(crate) struct ShebangDirective<'a>(&'a str);
 
 impl<'a> ShebangDirective<'a> {
     /// Parse a shebang directive from a line, or return `None` if the line does not contain a
@@ -17,9 +12,6 @@ impl<'a> ShebangDirective<'a> {
     pub(crate) fn try_extract(line: &'a str) -> Option<Self> {
         let mut cursor = Cursor::new(line);
 
-        // Trim whitespace.
-        cursor.eat_while(is_python_whitespace);
-
         // Trim the `#!` prefix.
         if !cursor.eat_char('#') {
             return None;
@@ -28,10 +20,15 @@ impl<'a> ShebangDirective<'a> {
             return None;
         }
 
-        Some(Self {
-            offset: line.text_len() - cursor.text_len(),
-            contents: cursor.chars().as_str(),
-        })
+        Some(Self(cursor.chars().as_str()))
+    }
+}
+
+impl Deref for ShebangDirective<'_> {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        self.0
     }
 }
 
@@ -59,6 +56,12 @@ mod tests {
         assert_debug_snapshot!(ShebangDirective::try_extract(source));
     }
 
+    #[test]
+    fn shebang_match_trailing_comment() {
+        let source = "#!/usr/bin/env python # trailing comment";
+        assert_debug_snapshot!(ShebangDirective::try_extract(source));
+    }
+
     #[test]
     fn shebang_leading_space() {
         let source = "  #!/usr/bin/env python";