All the actions, file dialogs and message dialogs that are specific to
the application are removed from `main.qml` and placed instead in
`Application.qml`.
Only elements and functions related to the main window remain in
`main.qml`. As such, the `ensureSaved` and `ensureNotComputing` functions,
used when closing the main window, remain in `main.qml`.
Message dialogs that may be opened by these functions however are moved
to `Application.qml` as they are application-specific and can't be opened
on the homepage.
Application dialogs that may need to be called when triggering the closure
of the main window are aliased from `Application.qml` to remain callable
through the `StackView`.
