Plugins - Added platform support

Settings - Fixed updating issues in plugin tab
UI - Don't initialize in design mode
UI - Move ReactiveCoreWindow to Artemis.Shared
Window service - Return window created by ShowWindow
Window service - Added CreateOpenFileDialog API

src/Artemis.UI/Screens/Sidebar/Dialogs/ProfileConfigurationEditView.axaml.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Disposables;
+using Artemis.UI.Shared;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;