bpo-42800: add audit hooks for f_code and tb_frame (GH-24182)

Accessing the following attributes will now fire PEP 578 style audit hooks as ("object.__getattr__", obj, name):
* PyTracebackObject: tb_frame
* PyFrameObject: f_code
* PyGenObject: gi_code, gi_frame
* PyCoroObject: cr_code, cr_frame
* PyAsyncGenObject: ag_code, ag_frame
Add an AUDIT_READ attribute flag aliased to READ_RESTRICTED.
Update obsolete flag documentation.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 5920ed8..5c33746 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -13,7 +13,7 @@
 
 static PyMemberDef frame_memberlist[] = {
     {"f_back",          T_OBJECT,       OFF(f_back),      READONLY},
-    {"f_code",          T_OBJECT,       OFF(f_code),      READONLY},
+    {"f_code",          T_OBJECT,       OFF(f_code),      READONLY|AUDIT_READ},
     {"f_builtins",      T_OBJECT,       OFF(f_builtins),  READONLY},
     {"f_globals",       T_OBJECT,       OFF(f_globals),   READONLY},
     {"f_trace_lines",   T_BOOL,         OFF(f_trace_lines), 0},