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/AnimalSettings.cs

@@ -0,0 +1,18 @@
+using System.ComponentModel;
+using Spectre.Console.Cli;
+
+namespace Spectre.Console.Tests.Data
+{
+    public abstract class AnimalSettings : CommandSettings
+    {
+        [CommandOption("-a|--alive|--not-dead")]
+        [Description("Indicates whether or not the animal is alive.")]
+        public bool IsAlive { get; set; }
+
+        [CommandArgument(1, "[LEGS]")]
+        [Description("The number of legs.")]
+        [EvenNumberValidator("Animals must have an even number of legs.")]
+        [PositiveNumberValidator("Number of legs must be greater than 0.")]
+        public int Legs { get; set; }
+    }
+}