bpo-44113: Deprecate old functions to config Python init (GH-26060)

Deprecate the following functions to configure the Python
initialization:

* PySys_AddWarnOption()
* PySys_AddWarnOptionUnicode()
* PySys_AddXOption()
* PySys_HasWarnOptions()
* Py_SetPath()
* Py_SetProgramName()
* Py_SetPythonHome()
* Py_SetStandardStreamEncoding()
* _Py_SetProgramFullPath()

Use the new PyConfig API of the Python Initialization Configuration
instead (PEP 587).

Doc/c-api/init.rst

@@ -323,6 +323,11 @@ Process-wide parameters
       single: main()
       triple: stdin; stdout; sdterr
 
+   This API is kept for backward compatibility: setting
+   :c:member:`PyConfig.stdio_encoding` and :c:member:`PyConfig.stdio_errors`
+   should be used instead, see :ref:`Python Initialization Configuration
+   <init-config>`.
+
    This function should be called before :c:func:`Py_Initialize`, if it is
    called at all. It specifies which encoding and error handling to use
    with standard IO, with the same meanings as in :func:`str.encode`.
@@ -345,6 +350,8 @@ Process-wide parameters
 
    .. versionadded:: 3.4
 
+   .. deprecated:: 3.11
+
 
 .. c:function:: void Py_SetProgramName(const wchar_t *name)
 
@@ -353,6 +360,10 @@ Process-wide parameters
       single: main()
       single: Py_GetPath()
 
+   This API is kept for backward compatibility: setting
+   :c:member:`PyConfig.program_name` should be used instead, see :ref:`Python
+   Initialization Configuration <init-config>`.
+
    This function should be called before :c:func:`Py_Initialize` is called for
    the first time, if it is called at all.  It tells the interpreter the value
    of the ``argv[0]`` argument to the :c:func:`main` function of the program
@@ -367,6 +378,8 @@ Process-wide parameters
    Use :c:func:`Py_DecodeLocale` to decode a bytes string to get a
    :c:type:`wchar_*` string.
 
+   .. deprecated:: 3.11
+
 
 .. c:function:: wchar* Py_GetProgramName()
 
@@ -495,6 +508,11 @@ Process-wide parameters
       single: path (in module sys)
       single: Py_GetPath()
 
+   This API is kept for backward compatibility: setting
+   :c:member:`PyConfig.module_search_paths` and
+   :c:member:`PyConfig.module_search_paths_set` should be used instead, see
+   :ref:`Python Initialization Configuration <init-config>`.
+
    Set the default module search path.  If this function is called before
    :c:func:`Py_Initialize`, then :c:func:`Py_GetPath` won't attempt to compute a
    default search path but uses the one provided instead.  This is useful if
@@ -518,6 +536,8 @@ Process-wide parameters
       The program full path is now used for :data:`sys.executable`, instead
       of the program name.
 
+   .. deprecated:: 3.11
+
 
 .. c:function:: const char* Py_GetVersion()
 
@@ -617,6 +637,9 @@ Process-wide parameters
    Use :c:func:`Py_DecodeLocale` to decode a bytes string to get a
    :c:type:`wchar_*` string.
 
+   See also :c:member:`PyConfig.orig_argv` and :c:member:`PyConfig.argv`
+   members of the :ref:`Python Initialization Configuration <init-config>`.
+
    .. note::
       It is recommended that applications embedding the Python interpreter
       for purposes other than executing a single script pass ``0`` as *updatepath*,
@@ -644,11 +667,18 @@ Process-wide parameters
    Use :c:func:`Py_DecodeLocale` to decode a bytes string to get a
    :c:type:`wchar_*` string.
 
+   See also :c:member:`PyConfig.orig_argv` and :c:member:`PyConfig.argv`
+   members of the :ref:`Python Initialization Configuration <init-config>`.
+
    .. versionchanged:: 3.4 The *updatepath* value depends on :option:`-I`.
 
 
 .. c:function:: void Py_SetPythonHome(const wchar_t *home)
 
+   This API is kept for backward compatibility: setting
+   :c:member:`PyConfig.home` should be used instead, see :ref:`Python
+   Initialization Configuration <init-config>`.
+
    Set the default "home" directory, that is, the location of the standard
    Python libraries.  See :envvar:`PYTHONHOME` for the meaning of the
    argument string.
@@ -661,6 +691,8 @@ Process-wide parameters
    Use :c:func:`Py_DecodeLocale` to decode a bytes string to get a
    :c:type:`wchar_*` string.
 
+   .. deprecated:: 3.11
+
 
 .. c:function:: w_char* Py_GetPythonHome()