Add capability-first account and calendar setup flow

Wino.Calendar.ViewModels/CalendarAppShellViewModel.cs

@@ -299,6 +299,9 @@ public partial class CalendarAppShellViewModel : CalendarBaseViewModel,
 
         foreach (var account in accounts)
         {
+            if (!GroupedAccountCalendarViewModel.SupportsCalendar(account))
+                continue;
+
             var accountCalendars = await _calendarService.GetAccountCalendarsAsync(account.Id).ConfigureAwait(false);
             var calendarViewModels = accountCalendars.Select(calendar => new AccountCalendarViewModel(account, calendar)).ToList();
             var groupedAccountCalendarViewModel = new GroupedAccountCalendarViewModel(account, calendarViewModels);

Wino.Calendar.ViewModels/CalendarEventComposePageViewModel.cs

@@ -408,6 +408,9 @@ public partial class CalendarEventComposePageViewModel : CalendarBaseViewModel
 
         foreach (var account in accounts)
         {
+            if (!GroupedAccountCalendarViewModel.SupportsCalendar(account))
+                continue;
+
             var calendars = await _calendarService.GetAccountCalendarsAsync(account.Id).ConfigureAwait(false);
             var viewModels = calendars
                 .Select(calendar => new AccountCalendarViewModel(account, calendar))

Wino.Calendar.ViewModels/Data/GroupedAccountCalendarViewModel.cs

@@ -17,6 +17,9 @@ public partial class GroupedAccountCalendarViewModel : ObservableObject
     public MailAccount Account { get; }
     public ObservableCollection<AccountCalendarViewModel> AccountCalendars { get; }
 
+    public static bool SupportsCalendar(MailAccount account)
+        => account?.IsCalendarAccessGranted == true;
+
     public GroupedAccountCalendarViewModel(MailAccount account, IEnumerable<AccountCalendarViewModel> calendarViewModels)
     {
         Account = account;