Remove the Value(Type) C++ constructor again

This theoretically makes sense for types that have default values, but
for example Value::Model requires a pointer Rc. But since we provide concrete constructors this
should not be needed.

api/sixtyfps-cpp/include/sixtyfps_interpreter.h

@@ -106,7 +106,6 @@ public:
         cbindgen_private::sixtyfps_interpreter_value_new_brush(&brush, &inner);
     }
     // Value(const Struct &);
-    explicit Value(Type);
 
     Type type() const { return cbindgen_private::sixtyfps_interpreter_value_type(&inner); }