using video_model.rs and presentation_model.rs

These are hopefully a better alternative than the cpp counterparts
after some more time

src/qml/presenter/Library.qml

@@ -65,7 +65,7 @@ Item {
                 itemIcon: "folder-videos-symbolic"
                 itemSubtitle: {
                     if (fileValidation)
-                        model.filePath;
+                        model.path;
                     else
                         "file is missing"
                         }