Implement add and delete entries and groups

New command bar
Some layout changes
Some refactoring

ModernKeePass/ViewModels/Items/RecentItemVm.cs

@@ -0,0 +1,19 @@
+using System.ComponentModel;
+using Windows.UI.Xaml;
+
+namespace ModernKeePass.ViewModels
+{
+    public class RecentItemVm: INotifyPropertyChanged
+    {
+        public string Token { get; set; }
+        public string Name { get; set; }
+        public Visibility PasswordVisibility { get; set; } = Visibility.Collapsed;
+        
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public void NotifyPropertyChanged(string propertyName)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}