Implement add and delete entries and groups

New command bar
Some layout changes
Some refactoring

ModernKeePass/ViewModels/Items/MainMenuItemVm.cs

@@ -0,0 +1,29 @@
+using System;
+using Windows.UI.Xaml.Controls;
+using ModernKeePass.Interfaces;
+
+namespace ModernKeePass.ViewModels
+{
+    public class MainMenuItemVm: IIsEnabled
+    {
+        private string _title;
+
+        public string Title
+        {
+            get { return IsEnabled ? _title : _title + " - Coming soon"; }
+            set { _title = value; }
+        }
+
+        public Type PageType { get; set; }
+        public object Parameter { get; set; }
+        public Frame Destination { get; set; }
+        public int Group { get; set; } = 0;
+        public Symbol SymbolIcon { get; set; }
+        public bool IsEnabled => PageType != null;
+
+        public override string ToString()
+        {
+            return Title;
+        }
+    }
+}

ModernKeePass/ViewModels/Items/RecentItemVm.cs

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+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));
+        }
+    }
+}