Eliminate some Types entirely

src/NUnitEngine/nunit.engine.core/Communication/Transports/ITestAgentTransport.cs

@@ -8,9 +8,11 @@ namespace NUnit.Engine.Communication.Transports
     /// The ITestAgentTransport interface is implemented by a
     /// class providing communication for a TestAgent.
     /// </summary>
-    public interface ITestAgentTransport : ITransport
+    public interface ITestAgentTransport
     {
         TestAgent Agent { get; }
         ITestEngineRunner CreateRunner(TestPackage package);
+        bool Start();
+        void Stop();
     }
 }

src/NUnitEngine/nunit.engine/Communication/Transports/ITestAgencyTransport.cs

@@ -1,13 +1,17 @@
 // Copyright (c) Charlie Poole, Rob Prouse and Contributors. MIT License - see LICENSE.txt
 
+using System.Numerics;
+
 namespace NUnit.Engine.Communication.Transports
 {
     /// <summary>
     /// The ITestAgencyTransport interface is implemented by a
     /// class providing communication for a TestAgency.
     /// </summary>
-    public interface ITestAgencyTransport : ITransport
+    public interface ITestAgencyTransport
     {
         string ServerUrl { get; }
+        bool Start();
+        void Stop();
     }
 }