gh-107178: Add the C API tests for the Abstract Objects Layer (GH-107179)

Cover all the Mapping Protocol, almost all the Sequence Protocol
(except PySequence_Fast) and a part of the Object Protocol.

Move existing tests to Lib/test/test_capi/test_abstract.py and
Modules/_testcapi/abstract.c.

Add also tests for PyDict C API.

Lib/test/test_bytes.py

@@ -1354,7 +1354,7 @@ class ByteArrayTest(BaseBytesTest, unittest.TestCase):
             except ValueError:
                 pass
             try:
-                setitem(b, 0, None)
+                setitem(b, 0, object())
                 self.fail("Didn't raise TypeError")
             except TypeError:
                 pass