stub out various pages

src/App/Pages/BaseViewModel.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace Bit.App.Pages
+{
+    public abstract class BaseViewModel : INotifyPropertyChanged
+    {
+        private string _pageTitle = string.Empty;
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public string PageTitle
+        {
+            get => _pageTitle;
+            set => SetProperty(ref _pageTitle, value);
+        }
+
+        protected bool SetProperty<T>(ref T backingStore, T value, [CallerMemberName]string propertyName = "",
+            Action onChanged = null)
+        {
+            if(EqualityComparer<T>.Default.Equals(backingStore, value))
+            {
+                return false;
+            }
+            backingStore = value;
+            onChanged?.Invoke();
+            OnPropertyChanged(propertyName);
+            return true;
+        }
+
+        protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}