fix: call the EssentialsDevice custom activate

`CrestronGenericBaseDevice` was NOT calling `base.CustomActivate()` in
it's `CustomActivate` override, causing the
`CreateMobileControlMessengers` method to not be called as expected when
plugin devices were inheriting from `CrestronGenericBaseDevice` or
`CrestronGenericBridgeableBaseDevice`.

src/PepperDash.Essentials.Core/Crestron/CrestronGenericBaseDevice.cs

@@ -104,7 +104,7 @@ namespace PepperDash.Essentials.Core
             Hardware.OnlineStatusChange += Hardware_OnlineStatusChange;
             CommunicationMonitor.Start();    
 
-			return true;
+			return base.CustomActivate();
 		}
 
 		/// <summary>