[flake8-simplify] Implement enumerate-for-loop (SIM113) (#7777)

Implements SIM113 from #998

Added tests
Limitations 
   - No fix yet
   - Only flag cases where index variable immediately precede `for` loop

@charliermarsh please review and let me know any improvements

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/ruff_python_semantic/src/analyze/typing.rs

@@ -645,6 +645,24 @@ pub fn resolve_assignment<'a>(
 pub fn find_assigned_value<'a>(symbol: &str, semantic: &'a SemanticModel<'a>) -> Option<&'a Expr> {
     let binding_id = semantic.lookup_symbol(symbol)?;
     let binding = semantic.binding(binding_id);
+    find_binding_value(symbol, binding, semantic)
+}
+
+/// Find the assigned [`Expr`] for a given [`Binding`], if any.
+///
+/// For example given:
+/// ```python
+///  foo = 42
+///  (bar, bla) = 1, "str"
+/// ```
+///
+/// This function will return a `NumberLiteral` with value `Int(42)` when called with `foo` and a
+/// `StringLiteral` with value `"str"` when called with `bla`.
+pub fn find_binding_value<'a>(
+    symbol: &str,
+    binding: &Binding,
+    semantic: &'a SemanticModel,
+) -> Option<&'a Expr> {
     match binding.kind {
         // Ex) `x := 1`
         BindingKind::NamedExprAssignment => {

crates/ruff_python_semantic/src/scope.rs

@@ -129,6 +129,11 @@ impl<'a> Scope<'a> {
         self.shadowed_bindings.get(&id).copied()
     }
 
+    /// Returns an iterator over all bindings that the given binding shadows, including itself.
+    pub fn shadowed_bindings(&self, id: BindingId) -> impl Iterator<Item = BindingId> + '_ {
+        std::iter::successors(Some(id), |id| self.shadowed_bindings.get(id).copied())
+    }
+
     /// Adds a reference to a star import (e.g., `from sys import *`) to this scope.
     pub fn add_star_import(&mut self, import: StarImport<'a>) {
         self.star_imports.push(import);