bpo-35713: Rework Python initialization (GH-11647)

bpo-35713: Rework Python initialization (GH-11647)

* The PyByteArray_Init() and PyByteArray_Fini() functions have been
  removed. They did nothing since Python 2.7.4 and Python 3.2.0, were
  excluded from the limited API (stable ABI), and were not
  documented.
* Move "_PyXXX_Init()" and "_PyXXX_Fini()" declarations from
  Include/cpython/pylifecycle.h to
  Include/internal/pycore_pylifecycle.h. Replace
  "PyAPI_FUNC(TYPE)" with "extern TYPE".
* _PyExc_Init() now returns an error on failure rather than calling
  Py_FatalError(). Move macros inside _PyExc_Init() and undefine them
  when done. Rewrite macros to make them look more like statement:
  add ";" when using them, add "do { ... } while (0)".
* _PyUnicode_Init() now returns a _PyInitError error rather than call
  Py_FatalError().
* Move stdin check from _PySys_BeginInit() to init_sys_streams().
* _Py_ReadyTypes() now returns a _PyInitError error rather than
  calling Py_FatalError().