Lost fork support for busybox in newer windows builds

[crossmeta]

With newer windows builds after 14393 busybox fork is not working as expected. The forked process would silently exit and ash functionality is broken. The rest of the features are working as expected.

The fork functionality is dependent on RtlCloneUserProcess and we don't know how to use it with the newer builds. On other hand with Windows 2019 (17763) the WSL bash can recognize crossmeta namespace.