Feature/wait for multiple

[LuizGOCunha]

Hey SeleniumLibrary team!

I have been using your library for python applications for almost two years now and felt I could maybe give a hand in the project itself.

The idea for this feature comes from one of the bots we've produced in my company, where we have a method that expects to be in one of two pages, so a wait for a single element does not work.

I'm very new to contributions, in fact this is my first one, so feel free to share any feedback about it.

Also, let me know if any other adjustments are required to make this method accessible for the RobotFramework language.

Have a good one!