The py.exe launcher now supportsinstall on demand for versions we have in the Store.

There's now a 3.12 alpha available (unlisted), so we should add an entry to the table in the launcher for it. The ID is9NCVDN91XZQP

This can be backported, as the launcher isn't part of the Python runtime and this won't have any impact on existing functionality (assuming the change is correct ;) )