RFC: Drop native Windows support for WSL2

There are many problems derived from supporting native Windows: since we are dealing with a lot of lower level paths and files and bytes handling we are exposed to many of the subtle differences between POSIX and Windows. As a result there is a lot of code that just handles all these quirks.
With the advent of a decent POSIX support in Windows 10, I would like to drop entirely native Windows support and only support WSL. This basically means that we support Linux on Windows. This would simplify the codebase vastly, as well as the CI and tests.

This means that WSL https://docs.microsoft.com/en-us/windows/wsl/install-win10 would become a requirement on Windows.