bpo-41746: Add type information to asdl_seq objects (GH-22223)

* Add new capability to the PEG parser to type variable assignments. For instance:
```
       | a[asdl_stmt_seq*]=';'.small_stmt+ [';'] NEWLINE { a }
```

* Add new sequence types from the asdl definition (automatically generated)
* Make `asdl_seq` type a generic aliasing pointer type.
* Create a new `asdl_generic_seq` for the generic case using `void*`.
* The old `asdl_seq_GET`/`ast_seq_SET` macros now are typed.
* New `asdl_seq_GET_UNTYPED`/`ast_seq_SET_UNTYPED` macros for dealing with generic sequences.
* Changes all possible `asdl_seq` types to use specific versions everywhere.

Author: pablogsal

Doc/tools/extensions/peg_highlight.py

@@ -43,7 +43,7 @@ class PEGLexer(RegexLexer):
             (r"'\W+?'", Text),
             (r'"\W+?"', Text),
         ],
-        "variables": [(_name + _text_ws + "(=)", bygroups(None, None, None),),],
+        "variables": [(_name + _text_ws + r"(\[.*\])?" + _text_ws + "(=)", bygroups(None, None, None, None, None),),],
         "invalids": [
             (r"^(\s+\|\s+invalid_\w+\s*\n)", bygroups(None)),
             (r"^(\s+\|\s+incorrect_\w+\s*\n)", bygroups(None)),