[BH-861] Cleanup Application split - part I

1. Prepare Pure and Bell specific `Application`
   classes and add them to `app` target:

- `products/BellHybrid/apps/Application.cpp`
- `products/PurePhone/apps/Application.cpp`

2. Update `CMakeLists.txt` files.
3. Move `ApplicationBell` implementation to Bell-specific
   `Application` class and remove `ApplicationBell` files.
4. Change Bell apps parent classes from `ApplicationBell`
  to Bell-specific `Application` class.
5. Rename `Application` to `ApplicationCommon` in the rest of the files.

module-apps/application-notes/model/NotesListModel.cpp

@@ -14,10 +14,11 @@
 
 namespace app::notes
 {
-    NotesListItemProvider::NotesListItemProvider(Application *app) : DatabaseModel(app)
+    NotesListItemProvider::NotesListItemProvider(ApplicationCommon *app) : DatabaseModel(app)
     {}
 
-    NotesListModel::NotesListModel(app::Application *app, std::shared_ptr<AbstractNotesRepository> notesRepository)
+    NotesListModel::NotesListModel(app::ApplicationCommon *app,
+                                   std::shared_ptr<AbstractNotesRepository> notesRepository)
         : NotesListItemProvider(app), notesRepository{std::move(notesRepository)}
     {}