bpo-40477: macOS Python Launcher app fixes for recent macOS releases (GH-30348)

This change solves two problems encountered by users of the macOS Python Launcher app on recent macOS releases (10.14+):

- The launcher app was no longer able to launch the macOS Terminal.app to run a script.

- Even if Terminal.app was already launched, the launcher app was unable to send an Apple Event to Terminal.app to open and run Python with the desired .py file.