fix(Log4Net): Implement new Append method on GoogleStackDriver

[robertvoinescu-work]

Using log4net 3.3.0 should have Append(IEnumerable<LoggingEvent>) implemented otherwise the bulk append method resolves to multiple single log entry appends (breaking some of our tests).

[gemini-code-assist]

Code Review

This pull request refactors the GoogleStackdriverAppender by introducing a new Append overload that accepts IEnumerable and updating the existing array-based Append method to delegate to it. Feedback suggests adding a null check for the loggingEvents parameter in the new method to enhance robustness against null inputs.

[gemini-code-assist]

The new Append(IEnumerable<LoggingEvent> loggingEvents) method should ideally include a null check for the loggingEvents parameter before accessing it or checking _isActivated, especially since it is a protected method that could be called by subclasses or directly within the class. Although log4net typically ensures non-null arguments in its pipeline, adding a guard clause improves robustness.

        protected override void Append(IEnumerable<LoggingEvent> loggingEvents)
        {
            if (loggingEvents == null)
            {
                return;
            }
            if (!_isActivated)