bpo-35134: Add Include/cpython/bytesobject.h file (GH-18494)

Add Include/cpython/bytearrayobject.h and
Include/cpython/bytesobject.h header files.

Move CPython C API from Include/bytesobject.h into a new
Include/cpython/bytesobject.h header file which is included by
Include/bytesobject.h. Do a similar change for
Include/bytearrayobject.h.
diff --git a/PCbuild/pythoncore.vcxproj b/PCbuild/pythoncore.vcxproj
index 7d597bc..9e6323f 100644
--- a/PCbuild/pythoncore.vcxproj
+++ b/PCbuild/pythoncore.vcxproj
@@ -126,6 +126,8 @@
     <ClInclude Include="..\Include\complexobject.h" />
     <ClInclude Include="..\Include\context.h" />
     <ClInclude Include="..\Include\cpython\abstract.h" />
+    <ClInclude Include="..\Include\cpython\bytearrayobject.h" />
+    <ClInclude Include="..\Include\cpython\bytesobject.h" />
     <ClInclude Include="..\Include\cpython\ceval.h" />
     <ClInclude Include="..\Include\cpython\dictobject.h" />
     <ClInclude Include="..\Include\cpython\fileobject.h" />