gh-144169: Fix three crashes in AST objects with non-str kwargs

[JelleZijlstra]

• Issue: ast: Segfault in node constructor when passing non-string keyword arguments #144169

[vstinner]

I closed my PR #144177 since this one is more complete.

[vstinner]

LGTM. I just left minor suggestions.

[vstinner]

Since we are modifying the error message, you must use the safer %T format:

Suggested change

	"%.400s got multiple values for argument %R",
	Py_TYPE(self)->tp_name, key);
	"%T got multiple values for argument %R",
	self, key);

Same remark for the two other changes below.

[JelleZijlstra]

It looks like this changes the error message to include the module name:

$ python3.14 -Wall -c 'import ast; ast.Name(idx=3)'
<string>:1: DeprecationWarning: Name.__init__ got an unexpected keyword argument 'idx'. Support for arbitrary keyword arguments is deprecated and will be removed in Python 3.15.
<string>:1: DeprecationWarning: Name.__init__ missing 1 required positional argument: 'id'. This will become an error in Python 3.15.
$ ./python.exe -Wall -c 'import ast; ast.Name(idx=3)'
<string>:1: DeprecationWarning: ast.Name.__init__ got an unexpected keyword argument 'idx'. Support for arbitrary keyword arguments is deprecated and will be removed in Python 3.15.
<string>:1: DeprecationWarning: ast.Name.__init__ missing 1 required positional argument: 'id'. This will become an error in Python 3.15.

I feel like that's a change we should only make in 3.15, not in the bugfix releases.

Why is %T safer?