Packaging: Add a ZipApps section #1063

I could do a PR based on the following sources, assuming you'd merge it (i.e. the effort won't be wasted).

• Building Zipapps (PEP 441)
• Packaging Python EXecutables (PEX)
• Installation With PEX
• Enabling Easy Zipapp Installs on Windows
• Bundling Python Dependencies in a ZIP Archive