Add config-driven action system (launch, url) with factory pattern

host-app/MacroPad.Host/LaunchAction.cs

@@ -0,0 +1,12 @@
+using System.Diagnostics;
+
+public class LaunchAction : IAction
+{
+    private readonly string _target;
+    public LaunchAction(string target) => _target = target;
+
+    public void Execute()
+    {
+        Process.Start(new ProcessStartInfo(_target) { UseShellExecute = true });
+    }
+}