gh-132781: Cleanup Code Related to NotShareableError (gh-132782)

The following are added to the internal C-API:

* _PyErr_FormatV()
* _PyErr_SetModuleNotFoundError()
* _PyXIData_GetNotShareableErrorType()
* _PyXIData_FormatNotShareableError()

We also drop _PyXIData_lookup_context_t and _PyXIData_GetLookupContext().