py/objmodule: Add a table of built-in modules with delegation.

This replaces the previous QSTR_null entry in the globals dict which could
leak out to Python (e.g. via iteration of mod.__dict__) and could lead to
crashes.

It results in smaller code size at the expense of turning a lookup into a
loop, but the list it is looping over likely only contains one or two
elements.

To allow a module to register its custom attr function it can use the new
`MP_REGISTER_MODULE_DELEGATION` macro.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

py/makeqstrdefs.py

@@ -93,7 +93,9 @@ def process_file(f):
     elif args.mode == _MODE_COMPRESS:
         re_match = re.compile(r'MP_COMPRESSED_ROM_TEXT\("([^"]*)"\)')
     elif args.mode == _MODE_MODULE:
-        re_match = re.compile(r"MP_REGISTER_(?:EXTENSIBLE_)?MODULE\(.*?,\s*.*?\);")
+        re_match = re.compile(
+            r"(?:MP_REGISTER_MODULE|MP_REGISTER_EXTENSIBLE_MODULE|MP_REGISTER_MODULE_DELEGATION)\(.*?,\s*.*?\);"
+        )
     elif args.mode == _MODE_ROOT_POINTER:
         re_match = re.compile(r"MP_REGISTER_ROOT_POINTER\(.*?\);")
     output = []