Add @disjoint_base decorator in the stdlib (#14599)

And fix some other new stubtest finds.

stdlib/pathlib/__init__.pyi

@@ -146,6 +146,7 @@ class Path(PurePath):
         __slots__ = ()
     else:
         __slots__ = ("_accessor",)
+
     if sys.version_info >= (3, 12):
         def __new__(cls, *args: StrPath, **kwargs: Unused) -> Self: ...  # pyright: ignore[reportInconsistentConstructor]
     else: