This adds a hidden `completion` subcommand to coreutils. When invoked with
`coreutils completion <utility> <shell>` a completion file will be printed
to stdout. When running `make install` those files will be created for all
utilities and copied to the appropriate locations.
`make install` will install completions for zsh, fish and bash; however,
clap also supports generating completions for powershell and elvish.
With this patch all utilities are required to have a publich uu_app function
that returns a clap::App in addition to the uumain function.
The binary was rename from uutils to coreutils in that commit
52ae491fcd
but the makefile to run the busybox test wasn't updated
This commit update the makefile to use the correct binary name.
It also update the busybox to the 1.32.1 version and fix the makefile
to run all the busybox tests instead of stopping after the failed exe
