Float fewer xwayland windows v2

[tewkanz]

Assuming that two XWayland windows with the same process ID are parent and child can also cause new instances of the same application to be treated like child windows when they really represent new applications. For example, clicking the New Window option in VSCode creates a floating window instead of tiling a new instance of the application.

This pull request updates pywm to only match up PIDs for certain window types that are expected to be child windows.