gh-117398: Use Per-Interpreter State for the _datetime Static Types (gh-119929)

We make use of the same mechanism that we use for the static builtin types.  This required a few tweaks.

The relevant code could use some cleanup but I opted to avoid the significant churn in this change.  I'll tackle that separately.

This change is the final piece needed to make _datetime support multiple interpreters.  I've updated the module slot accordingly.

Objects/exceptions.c

@@ -3725,7 +3725,7 @@ _PyExc_FiniTypes(PyInterpreterState *interp)
 {
     for (Py_ssize_t i=Py_ARRAY_LENGTH(static_exceptions) - 1; i >= 0; i--) {
         PyTypeObject *exc = static_exceptions[i].exc;
-        _PyStaticType_Dealloc(interp, exc);
+        _PyStaticType_FiniBuiltin(interp, exc);
     }
 }