Auto-update - Added update dialog

src/Artemis.UI/Screens/Settings/Dialogs/UpdateDialogView.xaml

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+<UserControl x:Class="Artemis.UI.Screens.Settings.Dialogs.UpdateDialogView"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:s="https://github.com/canton7/Stylet"
+             mc:Ignorable="d"
+             d:DesignHeight="450" d:DesignWidth="800">
+    <StackPanel Margin="16">
+        <TextBlock Style="{StaticResource MaterialDesignHeadline6TextBlock}" TextWrapping="Wrap">
+            Update available
+        </TextBlock>
+        <TextBlock Style="{StaticResource MaterialDesignSubtitle1TextBlock}"
+                   Foreground="{DynamicResource MaterialDesignBodyLight}"
+                   Margin="0 20 0 20"
+                   TextWrapping="Wrap">
+            A new Artemis update is available! 🥳<LineBreak/>
+            You are currently running build <Run Text="{Binding CurrentBuild, Mode=OneWay}" /> while the latest build is <Run Text="{Binding LatestBuild, Mode=OneWay}" />. <LineBreak/> <LineBreak/>
+            Updating Artemis will give you the latest bug(fixes), features and improvements.
+        </TextBlock>
+
+        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Margin="0 8 0 0">
+            <Button Style="{StaticResource MaterialDesignFlatButton}"
+                    Focusable="False"
+                    IsCancel="True"
+                    Command="{s:Action Cancel}"
+                    Content="LATER" />
+            <Button x:Name="ConfirmButton"
+                    Style="{StaticResource MaterialDesignFlatButton}"
+                    IsDefault="True"
+                    Focusable="True"
+                    Command="{s:Action Update}"
+                    Content="UPDATE" />
+        </StackPanel>
+
+    </StackPanel>
+</UserControl>

src/Artemis.UI/Screens/Settings/Dialogs/UpdateDialogViewModel.cs

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+using System.Threading.Tasks;
+using Artemis.Core;
+using Artemis.UI.Services;
+using Artemis.UI.Shared.Services;
+using Newtonsoft.Json.Linq;
+
+namespace Artemis.UI.Screens.Settings.Dialogs
+{
+    public class UpdateDialogViewModel : DialogViewModelBase
+    {
+        private readonly JToken _buildInfo;
+        private readonly IUpdateService _updateService;
+
+        public UpdateDialogViewModel(JToken buildInfo, IUpdateService updateService)
+        {
+            _buildInfo = buildInfo;
+            _updateService = updateService;
+            CurrentBuild = Constants.BuildInfo.BuildNumberDisplay;
+            LatestBuild = buildInfo?.SelectToken("value[0].buildNumber")?.Value<string>();
+        }
+
+        public string CurrentBuild { get; }
+        public string LatestBuild { get; }
+
+        public async Task Update()
+        {
+            await _updateService.ApplyUpdate();
+            Session.Close();
+        }
+    }
+}