Add definitions for match statement (#13147)

## Summary

This PR adds definition for match patterns.

## Test Plan

Update the existing test case for match statement symbols to verify that
the definitions are added as well.

crates/red_knot_python_semantic/src/node_key.rs

@@ -1,12 +1,18 @@
-use ruff_python_ast::{AnyNodeRef, NodeKind};
+use ruff_python_ast::{AnyNodeRef, Identifier, NodeKind};
 use ruff_text_size::{Ranged, TextRange};
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub(super) enum Kind {
+    Node(NodeKind),
+    Identifier,
+}
+
 /// Compact key for a node for use in a hash map.
 ///
 /// Compares two nodes by their kind and text range.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
 pub(super) struct NodeKey {
-    kind: NodeKind,
+    kind: Kind,
     range: TextRange,
 }
 
@@ -17,8 +23,15 @@ impl NodeKey {
     {
         let node = node.into();
         NodeKey {
-            kind: node.kind(),
+            kind: Kind::Node(node.kind()),
             range: node.range(),
         }
     }
+
+    pub(super) fn from_identifier(identifier: &Identifier) -> Self {
+        NodeKey {
+            kind: Kind::Identifier,
+            range: identifier.range(),
+        }
+    }
 }