Revamp ScanCode installation packages

We have several pesky installation issues that come up on certain new or different OS/arch/Python combos. This makes the initial experience really poor for some users.

We need to rethink the entire OS support and installation approach

The key is likely to always include a Python interpreter and to build installers as described in https://github.com/nexB/scancode-toolkit/issues/1703

- an AppImage for Linux
- some Windows installer (wix, NSIS?) for Windows (or use only a WSL2 AppImage? See https://github.com/nexB/scancode-toolkit/issues/2366 )
- an mpkg for macOS

With this we would limit the set of app archive we would create to one for each OS/arch combo.

The other usages should be developer type use that work from sources and a checkout.