Issue #18395: Rename ``_Py_char2wchar()`` to :c:func:`Py_DecodeLocale`, rename
``_Py_wchar2char()`` to :c:func:`Py_EncodeLocale`, and document these
functions.
Issue #18395, #22108: Update embedded Python examples to decode correctly
command line parameters: use Py_DecodeLocale() and PyUnicode_DecodeFSDefault().