[M] Create event wizard Scaffolding, Base logic and basic UI

[vtserej]

This is the first PR for CreateEventWizard. The logic to validate the steps is located in private void ValidateCurrentStep(object sender, PropertyChangedEventArgs e)

To enable is just uncomment this code in MainViewModel.cs

    private async Task CreateEvent()
    {
        await Shell.Current.GoToAsync(nameof(CreateEventPage));
        //await Shell.Current.GoToAsync(nameof(CreateEventPageNew));
    }

Any suggestions are welcome