bpo-40792: Make the result of PyNumber_Index() always having exact type int. (GH-20443)

Previously, the result could have been an instance of a subclass of int.

Also revert bpo-26202 and make attributes start, stop and step of the range
object having exact type int.

Add private function _PyNumber_Index() which preserves the old behavior
of PyNumber_Index() for performance to use it in the conversion functions
like PyLong_AsLong().
diff --git a/Lib/test/test_range.py b/Lib/test/test_range.py
index 30fa129..107c0e2 100644
--- a/Lib/test/test_range.py
+++ b/Lib/test/test_range.py
@@ -648,11 +648,17 @@
         self.assert_attrs(range(0, 10, 3), 0, 10, 3)
         self.assert_attrs(range(10, 0, -1), 10, 0, -1)
         self.assert_attrs(range(10, 0, -3), 10, 0, -3)
+        self.assert_attrs(range(True), 0, 1, 1)
+        self.assert_attrs(range(False, True), 0, 1, 1)
+        self.assert_attrs(range(False, True, True), 0, 1, 1)
 
     def assert_attrs(self, rangeobj, start, stop, step):
         self.assertEqual(rangeobj.start, start)
         self.assertEqual(rangeobj.stop, stop)
         self.assertEqual(rangeobj.step, step)
+        self.assertIs(type(rangeobj.start), int)
+        self.assertIs(type(rangeobj.stop), int)
+        self.assertIs(type(rangeobj.step), int)
 
         with self.assertRaises(AttributeError):
             rangeobj.start = 0