Support Qt for Python (PySide2) as an alternative to PyQt5

[Chaz6]

Qt for Python is the official binding and available under a LGPL license. https://www.qt.io/qt-for-python

[tombonner]

The reason for using PyQt5 is that IDA Pro uses it for its plugin architecture, and PE Tree started life as an IDA plugin, so it was natural to continue using PyQt5 for the standalone build.

I can certainly consider it though, will have to see if it's just a simple case of changing import statements or if it will require more work.