[Next Major] Delete bin/cordova_plist_to_config_xml script

[dpogue]

This old Python script was to help the transition from Cordova 1.x to newer Cordova versions using config.xml. I don't know what version of Python it even targets, but let's assume it's not recent. Cordova 1.x was over a decade ago and there's not really a feasible upgrade path from there to here simply by running a script.

I doubt anyone will notice or care if this goes missing, but to be safe let's do it as part of a major version bump.

There's also a block of code in CDVViewController that, if it fails to find config.xml, encourages people to run this script. We should remove that too.