bpo-40334: Support CO_FUTURE_BARRY_AS_BDFL in the new parser (GH-19721)

This commit also allows to pass flags to the new parser in all interfaces and fixes a bug in the parser generator that was causing to inline rules with actions, making them disappear.
diff --git a/Modules/_peg_parser.c b/Modules/_peg_parser.c
index cb5f9aa..e1ec36e 100644
--- a/Modules/_peg_parser.c
+++ b/Modules/_peg_parser.c
@@ -28,9 +28,10 @@
         return NULL;
     }
 
+    PyCompilerFlags flags = _PyCompilerFlags_INIT;
     PyObject *result = NULL;
 
-    mod_ty res = PyPegen_ASTFromFile(filename, mode, arena);
+    mod_ty res = PyPegen_ASTFromFile(filename, mode, &flags, arena);
     if (res == NULL) {
         goto error;
     }