feat: add AST checker engine framework with 9 Phase 1 engines

ast_checker/engines/base.py

@@ -0,0 +1,18 @@
+class BaseEngine:
+    @staticmethod
+    def collect_nodes(node, node_type):
+        results = []
+        if node.type == node_type:
+            results.append(node)
+        for child in node.children:
+            results.extend(BaseEngine.collect_nodes(child, node_type))
+        return results
+
+    @staticmethod
+    def has_node(node, node_type):
+        if node.type == node_type:
+            return True
+        return any(BaseEngine.has_node(child, node_type) for child in node.children)
+
+    def check(self, tree, rule, language, mapping) -> list[str]:
+        raise NotImplementedError