Refactored to require handlers to specify the components they rely on and to specify when they are ready. This fixes a lot of bugs with the UI when users try to press buttons while the application is still loading.

src/app/app_tests.rs

@@ -40,7 +40,6 @@ mod tests {
         },
       ]
     );
-    assert_str_eq!(app.title, "Managarr");
     assert_eq!(app.tick_until_poll, 400);
     assert_eq!(app.ticks_until_scroll, 4);
     assert_eq!(app.tick_count, 0);