Use OCCT Handle macro for Handle_ classes

This is the result of running OCCT's upgrade script provided
with OCCT 7.0. See
https://www.opencascade.com/content/freecad-occt710-and-windows-rtti-data-missing#comment-form
and
https://www.forum.freecadweb.org/viewtopic.php?f=4&t=21405&start=120#p169019
for why this is necessary for OCCT >= 7.1

src/Mod/Import/App/ImportOCAFAssembly.cpp

@@ -30,8 +30,6 @@
 # include <sstream>
 # include <Standard_Version.hxx>
 # include <BRep_Builder.hxx>
-# include <Handle_TDocStd_Document.hxx>
-# include <Handle_XCAFApp_Application.hxx>
 # include <TDocStd_Document.hxx>
 # include <XCAFApp_Application.hxx>
 # include <XCAFDoc_DocumentTool.hxx>
@@ -79,7 +77,7 @@
 using namespace Import;
 
 
-ImportOCAFAssembly::ImportOCAFAssembly(Handle_TDocStd_Document h, App::Document* d, const std::string& name, App::DocumentObject *target)
+ImportOCAFAssembly::ImportOCAFAssembly(Handle(TDocStd_Document) h, App::Document* d, const std::string& name, App::DocumentObject *target)
     : pDoc(h), 
       doc(d), 
       default_name(name),