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.
Turned application notes into separate library, specified
private and public include directories and dependencies,
removed application notes from Bell Hybrid target
Due to vfs deprecation there is need to remove all vfs calls from code. This PR covers module gui. There are some modifications in other modules included which are necessary because of build system issues.
