Add the possibility to register multiple interceptors (#1412)

Having the interceptors registered with the ITypeRegistrar also enables the usage of ITypeResolver in interceptors.

test/Spectre.Console.Cli.Tests/Unit/CommandAppTests.Interceptor.cs

@@ -0,0 +1,90 @@
+namespace Spectre.Console.Tests.Unit.Cli;
+
+public sealed partial class CommandAppTests
+{
+    public sealed class Interceptor
+    {
+        public sealed class NoCommand : Command<NoCommand.Settings>
+        {
+            public sealed class Settings : CommandSettings
+            {
+            }
+
+            public override int Execute(CommandContext context, Settings settings)
+            {
+                return 0;
+            }
+        }
+
+        public sealed class MyInterceptor : ICommandInterceptor
+        {
+            private readonly Action<CommandContext, CommandSettings> _action;
+
+            public MyInterceptor(Action<CommandContext, CommandSettings> action)
+            {
+                _action = action;
+            }
+
+            public void Intercept(CommandContext context, CommandSettings settings)
+            {
+                _action(context, settings);
+            }
+        }
+
+        public sealed class MyResultInterceptor : ICommandInterceptor
+        {
+            private readonly Func<CommandContext, CommandSettings, int, int> _function;
+
+            public MyResultInterceptor(Func<CommandContext, CommandSettings, int, int> function)
+            {
+                _function = function;
+            }
+
+            public void InterceptResult(CommandContext context, CommandSettings settings, ref int result)
+            {
+                result = _function(context, settings, result);
+            }
+        }
+
+        [Fact]
+        public void Should_Run_The_Interceptor()
+        {
+            // Given
+            var count = 0;
+            var app = new CommandApp<NoCommand>();
+            var interceptor = new MyInterceptor((_, _) =>
+            {
+                count += 1;
+            });
+            app.Configure(config => config.SetInterceptor(interceptor));
+
+            // When
+            app.Run(Array.Empty<string>());
+
+            // Then
+            count.ShouldBe(1); // to be sure
+        }
+
+        [Fact]
+        public void Should_Run_The_ResultInterceptor()
+        {
+            // Given
+            var count = 0;
+            const int Expected = 123;
+            var app = new CommandApp<NoCommand>();
+            var interceptor = new MyResultInterceptor((_, _, _) =>
+            {
+                count += 1;
+                return Expected;
+            });
+            app.Configure(config => config.SetInterceptor(interceptor));
+
+            // When
+            var actual = app.Run(Array.Empty<string>());
+
+            // Then
+            count.ShouldBe(1);
+            actual.ShouldBe(Expected);
+        }
+    }
+}