Moved analyzer tests to its own project

Also moves tests to `./test` which makes it possible
for all test projects to share the same .editorconfig
files and similar.

test/Spectre.Console.Tests/Data/Settings/LionSettings.cs

@@ -0,0 +1,16 @@
+using System.ComponentModel;
+using Spectre.Console.Cli;
+
+namespace Spectre.Console.Tests.Data
+{
+    public class LionSettings : CatSettings
+    {
+        [CommandArgument(0, "<TEETH>")]
+        [Description("The number of teeth the lion has.")]
+        public int Teeth { get; set; }
+
+        [CommandOption("-c <CHILDREN>")]
+        [Description("The number of children the lion has.")]
+        public int Children { get; set; }
+    }
+}