Reverting making .NET ICommandExecutor extend IDisposable

This change will reappear at some point. Downstream projects will need to
implement a `public void Dispose()` method on any classes that implement
ICommandExecutor to prevent breaking when this interface change is added
again. Fixes issue SeleniumHQ#5768.

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 : IDisposable
+    public interface ICommandExecutor
     {
         /// <summary>
         /// Gets the repository of objects containin information about commands.