Support workspace with Alpine Linux

workflow

#1

When you try to restore a workspace with an alpine linux base which DOES have a version of tar present from busybox in /bin/tar, it still gives the error:

GNU tar is not present in this image but it is required. Please install it to have workflow workspace capability.

This can be seen in this build log: https://circleci.com/gh/Microsoft/PartsUnlimitedMRPmicro/72


#2