Convert A13-2-1 to the new dataflow library

Author: jketema

cpp/autosar/src/rules/A13-2-1/AssignmentOperatorReturnThis.ql

@@ -16,7 +16,7 @@
 import cpp
 import codingstandards.cpp.autosar
 import codingstandards.cpp.Operator
-import semmle.code.cpp.dataflow.DataFlow
+import semmle.code.cpp.dataflow.new.DataFlow
 
 predicate returnsThisPointer(UserAssignmentOperator o) {
   exists(PointerDereferenceExpr p, ThisExpr t, ReturnStmt r |

cpp/autosar/test/rules/A13-2-1/AssignmentOperatorReturnThis.expected

@@ -1,4 +1,3 @@
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (AssignmentOperatorReturnThis.ql:25,5-13)
 | test.cpp:10:12:10:20 | operator= | User-defined assignment operator $@ does not return *this | test.cpp:10:12:10:20 | operator= |  user defined assignment operator |
 | test.cpp:17:11:17:19 | operator= | User-defined assignment operator $@ does not return *this | test.cpp:17:11:17:19 | operator= |  user defined assignment operator |
 | test.cpp:24:12:24:20 | operator= | User-defined assignment operator $@ does not return *this | test.cpp:24:12:24:20 | operator= |  user defined assignment operator |