[3.12] gh-122292: Split up Lib/test/test_ast.py into a couple of … (#122395)

[3.12] gh-122292: Split up ``Lib/test/test_ast.py`` into a couple of files (GH-122293)
(cherry picked from commit 9187484)

Author: Eclips4

Lib/test/test_ast/__init__.py

@@ -0,0 +1,7 @@
+import os
+
+from test import support
+
+
+def load_tests(*args):
+    return support.load_package_tests(os.path.dirname(__file__), *args)