Ensure external help options are mentioned in short help where available

[Gedochao]

Fixes #2798

scala-cli -h
Usage: scala-cli <COMMAND>
Scala CLI is a command-line tool to interact with the Scala language. It lets you compile, run and test your Scala code.

Main commands:
  clean                  Clean the workspace.
  compile                Compile Scala code.
  doc                    Generate Scaladoc documentation.
  fmt, format, scalafmt  Formats Scala code.
  repl, console          Fire-up a Scala REPL.
  run                    Compile and run Scala code.
  test                   Compile and test Scala code.

Miscellaneous commands:
  version  Prints the version of the Scala CLI and the default version of Scala.

Other commands:
  config                                        Configure global settings for Scala CLI.
  help                                          Print help message
  install completions, install-completions      Installs Scala CLI completions into your shell
  setup-ide                                     Generates a BSP file that you can import into your IDE.
  shebang                                       Like `run`, but handier for shebang scripts.
  uninstall                                     Uninstalls Scala CLI.
  uninstall completions, uninstall-completions  Uninstalls Scala CLI completions from your shell.
  update                                        Updates Scala CLI.

See 'scala-cli <command> --help' to read about a specific subcommand. To see full help run 'scala-cli <command> --help-full'.

To use launcher options, specify them before any other argument.
For example, to run another Scala CLI version, specify it with the '--cli-version' launcher option:
  scala-cli --cli-version <version> args

Launcher options:
  --cli-version nightly|version  Set the Scala CLI version
  --power                        Allows to use restricted & experimental features

Scala options:
  --scalac-help, --help-scalac        Show help for scalac. This is an alias for --scalac-option -help
  --scalac-verbose, --verbose-scalac  Turn verbosity on for scalac. This is an alias for --scalac-option -verbose

Help options:
  --help-js                    Show options for ScalaJS
  --help-native                Show options for ScalaNative
  --help-doc, --help-scaladoc  Show options for Scaladoc
  --help-repl, --repl-help     Show options for Scala REPL
  --help-fmt, --help-scalafmt  Show options for Scalafmt

When no subcommand is passed explicitly, an implicit subcommand is used based on context:
  - if the '--version' option is passed, it prints the 'version' subcommand output, unmodified by any other options
  - if any inputs were passed, it defaults to the 'run' subcommand
  - additionally, when no inputs were passed, it defaults to the 'run' subcommand in the following scenarios:
    - if a snippet was passed with any of the '--execute*' options
    - if a main class was passed with the '--main-class' option alongside an extra '--classpath'
  - otherwise, if no inputs were passed, it defaults to the 'repl' subcommand