Reduce the size of the boot2container image!
By removing unused functions in podman, and merging mcli in u-root's gobusybox binary (IT IS FINALLY WORKING!), we manage to slim it down by around 10%
Unfortunately, podman cannot also be merged in u-root's gobusybox binary for the following reasons:
- u-root requires CGO_ENABLED=0, which breaks podman's overlay driver
- u-root requires a project you can call "go build" in, which isn't the case of podman (this is probably solvable though)