screens: Remove displayapp parameter from screen

The DisplayApp class isn't used in the Screen base class and most
screens, so requiring it is pointless.

In this commit, DisplayApp pointers were added to screens which use it
and the explicit Screen constructor was removed in those screens.

src/displayapp/screens/List.cpp

@@ -17,7 +17,7 @@ List::List(uint8_t screenID,
            DisplayApp* app,
            Controllers::Settings& settingsController,
            std::array<Applications, MAXLISTITEMS>& applications)
-  : Screen(app), settingsController {settingsController}, pageIndicator(screenID, numScreens) {
+  : app {app}, settingsController {settingsController}, pageIndicator(screenID, numScreens) {
 
   // Set the background to Black
   lv_obj_set_style_local_bg_color(lv_scr_act(), LV_OBJ_PART_MAIN, LV_STATE_DEFAULT, lv_color_make(0, 0, 0));