Implement __iter__ for wxList iterator classes

[swt2c]

This fixes being able to use these classes in for loops, for example. Specifically it fixes the cmdproc tests with Python 3.13.1.

[swt2c]

@DietmarSchwertberger can you confirm this resolves the issues you were seeing with wxGlade too?

[DietmarSchwertberger]

@swt2c : Yes, that fixes the issue. Thanks. I will leave the workaround for some time, though.

Just checked why my minimal code sample was not able to reproduce the problem.
This one was failing:

children = [c for c in app.frame.notebook_1_pane_1.GetChildren()]

In my sample I was using this code, which was working:

for c in app.frame.notebook_1_pane_1.GetChildren():
    print(c)

I would have expected both to use the same iterator.

[swt2c]

I would have expected both to use the same iterator.

I think it's probably the difference between iter(x), which worked, and iter(iter(x)), which did not work, where x is a wxList class.