bpo-36763: _PyCoreConfig_SetPyArgv() preinitializes Python (GH-13037)

_PyCoreConfig_SetPyArgv() and _PyCoreConfig_SetWideString() now
pre-initialize Python if needed to ensure that the locale encoding is
properly configured.

* Add _Py_PreInitializeFromPyArgv() internal function.
* Add 'args' parameter to _Py_PreInitializeFromCoreConfig()