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/OptionalArgumentWithDefaultValueSettings.cs

@@ -0,0 +1,40 @@
+using System;
+using System.ComponentModel;
+using Spectre.Console.Cli;
+
+namespace Spectre.Console.Tests.Data
+{
+    public sealed class OptionalArgumentWithDefaultValueSettings : CommandSettings
+    {
+        [CommandArgument(0, "[GREETING]")]
+        [DefaultValue("Hello World")]
+        public string Greeting { get; set; }
+    }
+
+    public sealed class OptionalArgumentWithPropertyInitializerSettings : CommandSettings
+    {
+        [CommandArgument(0, "[NAMES]")]
+        public string[] Names { get; set; } = Array.Empty<string>();
+
+        [CommandOption("-c")]
+        public int Count { get; set; } = 1;
+
+        [CommandOption("-v")]
+        public int Value { get; set; } = 0;
+    }
+
+    public sealed class OptionalArgumentWithDefaultValueAndTypeConverterSettings : CommandSettings
+    {
+        [CommandArgument(0, "[GREETING]")]
+        [DefaultValue("5")]
+        [TypeConverter(typeof(StringToIntegerConverter))]
+        public int Greeting { get; set; }
+    }
+
+    public sealed class RequiredArgumentWithDefaultValueSettings : CommandSettings
+    {
+        [CommandArgument(0, "<GREETING>")]
+        [DefaultValue("Hello World")]
+        public string Greeting { get; set; }
+    }
+}