Internals: Carry 'with' clause as op4 on AstNodeFTaskRef (#7114)

op4 is now available to carry the 'with' clause explicitly instead of
being part of the argument lit. Will strengthen 'pinsp' to be
List[AstArg] next.

src/V3LinkLValue.cpp

@@ -336,6 +336,7 @@ class LinkLValueVisitor final : public VNVisitor {
                 iterate(pinp);
             }
         }
+        if (nodep->withp()) iterate(nodep->withp());
     }
     void visit(AstConstraint* nodep) override {
         VL_RESTORER(m_setIfRand);