gh-76785: Drop PyInterpreterID_Type (gh-117101)

I added it quite a while ago as a strategy for managing interpreter lifetimes relative to the PEP 554 (now 734) implementation.  Relatively recently I refactored that implementation to no longer rely on InterpreterID objects.  Thus now I'm removing it.

Author: ericsnowcurrently

Include/cpython/interpreteridobject.h

@@ -295,12 +295,11 @@ _PyInterpreterState_SetFinalizing(PyInterpreterState *interp, PyThreadState *tst
 }
 
 
-extern int64_t _PyInterpreterState_ObjectToID(PyObject *);
 
-// Export for the _xxinterpchannels module.
+// Exports for the _testinternalcapi module.
+PyAPI_FUNC(int64_t) _PyInterpreterState_ObjectToID(PyObject *);
 PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpID(int64_t);
 PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpIDObject(PyObject *);
-
 PyAPI_FUNC(int) _PyInterpreterState_IDInitref(PyInterpreterState *);
 PyAPI_FUNC(int) _PyInterpreterState_IDIncref(PyInterpreterState *);
 PyAPI_FUNC(void) _PyInterpreterState_IDDecref(PyInterpreterState *);