Add GUI template

- Add AvaloniaUI GUI template to the project
- Add missing newline to the CLI output

HyperbolicDownloaderGUI/App.axaml

@@ -0,0 +1,12 @@
+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:local="using:HyperbolicDownloaderGUI"
+             x:Class="HyperbolicDownloaderGUI.App">
+    <Application.DataTemplates>
+        <local:ViewLocator/>
+    </Application.DataTemplates>
+
+    <Application.Styles>
+        <FluentTheme Mode="Light"/>
+    </Application.Styles>
+</Application>