feat: auto alias subcmds with hyphens for underscores

[sigoden]

If the subcommand name contains _, argc will automaticly generate a alias (_ => -) for it.

#!/bin/bash
set -e

# @cmd
foo_bar() {
    echo OK
}

eval "$(argc --argc-eval "$0" "$@")"

$ prog -h
USAGE: prog<COMMAND>

COMMANDS:
  foo_bar  [aliases: foo-bar]

$ prog foo_bar
OK

$ grog foo-bar
OK