PHPUnit 10.x compatible TestListener

[jrfnl]

Handle the change from TestListener to Event system for the TestListener Polyfill.

As for the TestListeners... while I have the principle of it working without issues, the trouble I'm running into is the translation between the old Listener "events" and the new Events. There is no documentation available about this and finding which "old" events ended up triggering the test listener is not as straight forward as it seems (seemed).

I basically need a couple of days/week to research this in a lot more depth to make sure the implementation the Polyfills repo offers is comparable between PHPUnit < 10 and PHPUnit 10.x and what with there being quite a lot of other things on my plate, I haven't been able to find that time so far.

Also see #95