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/Unit/Cli/CommandAppTests.Version.cs

@@ -0,0 +1,37 @@
+using Shouldly;
+using Spectre.Console.Testing;
+using Spectre.Console.Tests.Data;
+using Xunit;
+
+namespace Spectre.Console.Tests.Unit.Cli
+{
+    public sealed partial class CommandAppTests
+    {
+        public sealed class Version
+        {
+            [Fact]
+            public void Should_Output_The_Version_To_The_Console()
+            {
+                // Given
+                var fixture = new CommandAppTester();
+                fixture.Configure(config =>
+                {
+                    config.AddBranch<AnimalSettings>("animal", animal =>
+                    {
+                        animal.AddBranch<MammalSettings>("mammal", mammal =>
+                        {
+                            mammal.AddCommand<DogCommand>("dog");
+                            mammal.AddCommand<HorseCommand>("horse");
+                        });
+                    });
+                });
+
+                // When
+                var result = fixture.Run(Constants.VersionCommand);
+
+                // Then
+                result.Output.ShouldStartWith("Spectre.Cli version ");
+            }
+        }
+    }
+}