Remove some unused pub functions (#11576)

## Summary

I left anything in `red-knot`, any `with_` methods, etc.

crates/ruff_python_ast/src/name.rs

@@ -59,10 +59,6 @@ impl<'a> QualifiedName<'a> {
         matches!(self.segments(), ["", ..])
     }
 
-    pub fn is_user_defined(&self) -> bool {
-        !self.is_builtin()
-    }
-
     /// If the call path is dot-prefixed, it's an unresolved relative import.
     /// Ex) `[".foo", "bar"]` -> `".foo.bar"`
     pub fn is_unresolved_import(&self) -> bool {

crates/ruff_python_ast/src/nodes.rs

@@ -3729,20 +3729,6 @@ impl fmt::Display for IpyEscapeKind {
 }
 
 impl IpyEscapeKind {
-    /// Returns the length of the escape kind token.
-    pub fn prefix_len(self) -> TextSize {
-        let len = match self {
-            IpyEscapeKind::Shell
-            | IpyEscapeKind::Magic
-            | IpyEscapeKind::Help
-            | IpyEscapeKind::Quote
-            | IpyEscapeKind::Quote2
-            | IpyEscapeKind::Paren => 1,
-            IpyEscapeKind::ShCap | IpyEscapeKind::Magic2 | IpyEscapeKind::Help2 => 2,
-        };
-        len.into()
-    }
-
     /// Returns `true` if the escape kind is help i.e., `?` or `??`.
     pub const fn is_help(self) -> bool {
         matches!(self, IpyEscapeKind::Help | IpyEscapeKind::Help2)

crates/ruff_python_ast/src/traversal.rs

@@ -79,15 +79,3 @@ pub fn next_sibling<'a>(stmt: &'a Stmt, suite: &'a Suite) -> Option<&'a Stmt> {
     }
     None
 }
-
-/// Given a [`Stmt`] and its containing [`Suite`], return the previous [`Stmt`] in the [`Suite`].
-pub fn prev_sibling<'a>(stmt: &'a Stmt, suite: &'a Suite) -> Option<&'a Stmt> {
-    let mut prev = None;
-    for sibling in suite {
-        if sibling == stmt {
-            return prev;
-        }
-        prev = Some(sibling);
-    }
-    None
-}