fix(update-alternatives): fix the "--help" parsing

While alternatives in Fedora produces the following output with alternatives --help:

alternatives version 1.26 - Copyright (C) 2001 Red Hat, Inc.
This may be freely redistributed under the terms of the GNU Public License.

usage: alternatives --install <link> <name> <path> <priority>
                    [--initscript <service>]
                    [--family <family>]
                    [--follower <follower_link> <follower_name> <follower_path>]*
       alternatives --remove <name> <path>
       alternatives --auto <name>
       alternatives --config <name>
       alternatives --display <name>
       alternatives --set <name> <path/family>
       alternatives --list
       alternatives --remove-all <name>
       alternatives --add-follower <name> <path> <follower_link> <follower_name> <follower_path>
       alternatives --remove-follower <name> <path> <follower_name>

common options: --verbose --test --help --usage --version --keep-missing --keep-foreign
                --altdir <directory> --admindir <directory>

an old version of update-alternatives (in debian12 container) seems to produce the following output

Usage: update-alternatives [<option> ...] <command>

Commands:
  --install <link> <name> <path> <priority>
    [--slave <link> <name> <path>] ...
                           add a group of alternatives to the system.
  --remove <name> <path>   remove <path> from the <name> group alternative.
  --remove-all <name>      remove <name> group from the alternatives system.
  --auto <name>            switch the master link <name> to automatic mode.
  --display <name>         display information about the <name> group.
  --query <name>           machine parseable version of --display <name>.
  --list <name>            display all targets of the <name> group.
  --get-selections         list master alternative names and their status.
  --set-selections         read alternative status from standard input.
  --config <name>          show alternatives for the <name> group and ask the
                           user to select which one to use.
  --set <name> <path>      set <path> as alternative for <name>.
  --all                    call --config on all alternatives.

<link> is the symlink pointing to /etc/alternatives/<name>.
  (e.g. /usr/bin/pager)
<name> is the master name for this link group.
  (e.g. pager)
<path> is the location of one of the alternative target files.
  (e.g. /usr/bin/less)
<priority> is an integer; options with higher numbers have higher priority in
  automatic mode.

Options:
  --altdir <directory>     change the alternatives directory.
  --admindir <directory>   change the administrative directory.
  --log <file>             change the log file.
  --force                  allow replacing files with alternative links.
  --skip-auto              skip prompt for alternatives correctly configured
                           in automatic mode (relevant for --config only)
  --quiet                  quiet operation, minimal output.
  --verbose                verbose operation, more output.
  --debug                  debug output, way more output.
  --help                   show this help message.
  --version                show the version."

I adjusted the PR to support both types.

scop / bash-completion

fix(update-alternatives): fix the "--help" parsing #1239