gh-113317: Move Argument Clinic converters to sub-modules

Move the following classes to new sub-modules:

* libclinic.return_converters:

  * CReturnConverterAutoRegister
  * CReturnConverter

* libclinic.int_converters:

  * bool_converter
  * char_converter
  * unsigned_char_converter
  * byte_converter
  * short_converter
  * unsigned_short_converter
  * int_converter
  * unsigned_int_converter
  * long_converter
  * unsigned_long_converter
  * long_long_converter
  * unsigned_long_long_converter
  * Py_ssize_t_converter
  * slice_index_converter
  * size_t_converter

* libclinic.obj_converters:

  * fildes_converter
  * float_converter
  * double_converter
  * Py_complex_converter
  * object_converter
  * buffer
  * rwbuffer
  * robuffer
  * str_converter
  * PyBytesObject_converter
  * PyByteArrayObject_converter
  * unicode_converter
  * Py_UNICODE_converter
  * Py_buffer_converter

* libclinic.misc_converters:

  * defining_class_converter
  * self_converter

Move also Null, NULL and TypeSet to libclinic.utils.

Tools/clinic/libclinic/__init__.py

@@ -32,6 +32,9 @@
     Sentinels,
     unspecified,
     unknown,
+    TypeSet,
+    Null,
+    NULL,
 )
 
 
@@ -68,6 +71,9 @@
     "Sentinels",
     "unspecified",
     "unknown",
+    "TypeSet",
+    "Null",
+    "NULL",
 ]
 
 

Tools/clinic/libclinic/converter.py

@@ -532,3 +532,22 @@ def add_include(self, name: str, reason: str,
 # these callables follow the same rules as those for "converters" above.
 # note however that they will never be called with keyword-only parameters.
 legacy_converters: ConverterDict = {}
+
+
+def add_legacy_c_converter(
+        format_unit: str,
+        **kwargs: Any
+) -> Callable[[CConverterClassT], CConverterClassT]:
+    """
+    Adds a legacy converter.
+    """
+    def closure(f: CConverterClassT) -> CConverterClassT:
+        added_f: Callable[..., CConverter]
+        if not kwargs:
+            added_f = f
+        else:
+            added_f = functools.partial(f, **kwargs)
+        if format_unit:
+            legacy_converters[format_unit] = added_f
+        return f
+    return closure

Tools/clinic/libclinic/function.py

@@ -6,8 +6,10 @@
 import inspect
 from typing import Final, Any, TYPE_CHECKING
 if TYPE_CHECKING:
-    from clinic import Clinic, CReturnConverter, self_converter
     from libclinic.converter import CConverter
+    from libclinic.misc_converters import self_converter
+    from libclinic.return_converter import CReturnConverter
+    from clinic import Clinic
 
 from libclinic import VersionTuple, unspecified