Reinstating ICommandExecutor descending from IDisposable in .NET

Now that the Appium project has implemented the methods required by an
implementation of IDisposable, this change can be made upstream in the
Selenium project. As this change has been rolled back once before to
accommodate downstream projects, it will be incumbent upon them to update
their libraries now, as it will not be rolled back again. In the case of
Appium, this is merely awaiting a binary release; other downstream
projects will be responsible for managing their own code changes and
release schedule.

dotnet/src/webdriver/Remote/ICommandExecutor.cs

@@ -23,7 +23,7 @@ namespace OpenQA.Selenium.Remote
     /// <summary>
     /// Provides a way to send commands to the remote server
     /// </summary>
-    public interface ICommandExecutor
+    public interface ICommandExecutor : IDisposable
     {
         /// <summary>
         /// Gets the repository of objects containin information about commands.