feature: adds support for HdSpXxx switchers

WIP: added support for HD-PS401, HD-PS402, HD-PS621 and HD-PS622,
pending testing with device.

essentials-framework/Essentials DM/Essentials_DM/Config/HdPsXxxPropertiesConfig.cs

@@ -0,0 +1,18 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+using PepperDash.Core;
+
+namespace PepperDash_Essentials_DM.Config
+{
+	public class HdPsXxxPropertiesConfig
+	{
+		[JsonProperty("control")]
+		public ControlPropertiesConfig Control { get; set; }
+
+		[JsonProperty("inputs")]
+		public Dictionary<uint, string> Inputs { get; set; } 
+
+		[JsonProperty("outputs")]
+		public Dictionary<uint, string> Outputs { get; set; } 
+	}
+}