[master] method never used: TasksViewModel.addNewTask()

The method `addNewTask()` in `TasksViewModel.kt` is never used. Though commented "Called by the Data Binding library and the FAB's click listener." The click listener of FAB is set in `TasksFragment.kt`, navigating to new page.

**TasksViewModel.kt**

```kotlin
/**
* Called by the Data Binding library and the FAB's click listener.
*/
fun addNewTask() {
_newTaskEvent.value = Event(Unit)
}
```

**TasksFragment.kt**
```kotlin
private fun setupFab() {
activity?.findViewById(R.id.add_task_fab)?.let {
it.setOnClickListener {
navigateToAddNewTask()
}
}
}

private fun navigateToAddNewTask() {
val action = TasksFragmentDirections
.actionTasksFragmentToAddEditTaskFragment(
null,
resources.getString(R.string.add_task)
)
findNavController().navigate(action)
}
```

Start in TasksViewModel.kt and TasksFragment.kt, then search for references to addNewTask() and the Data Binding callback. Confirm that the FAB still navigates through setupFab() and navigateToAddNewTask(); done means the unused method and any obsolete reference are removed without changing that navigation.

Written by the indexing model from the issue text.