Include launcher options in the help for the default and help sub-commands

[Gedochao]

Fixes #1698

Note: this adds the launcher options help to the default and help sub-commands only.
They probably should also smh be included in other sub-commands' help as well, but that'll be addressed separately.

▶ scala-cli --help
Usage: /Users/pchabelski/IdeaProjects/scala-cli/out/cli/base-image/nativeImage.dest/scala-cli <COMMAND>
Scala CLI is a command-line tool to interact with the Scala language. It lets you compile, run, test and package your Scala code.

Main commands:
  clean                  Clean the workspace
  compile                Compile Scala code
  dependency-update      Update dependencies in project
  doc                    Generate Scaladoc documentation
  fmt, format, scalafmt  Format Scala code
  repl, console          Fire-up a Scala REPL
  package                Compile and package Scala code
  publish
  publish local
  publish setup
  run                    Compile and run Scala code.
  test                   Compile and test Scala code

Miscellaneous commands:
  about    Print details about this application
  version  Print version

Other commands:
  export                                        Export current project to sbt or Mill
  help                                          Print help message
  install completions, install-completions      Installs completions into your shell
  github secret create, gh secret create
  github secret list, gh secret list
  setup-ide                                     Generate a BSP file that you can import into your IDE
  shebang                                       Like `run`, but more handy from shebang scripts
  uninstall                                     Uninstall scala-cli - only works when installed by the installation script
  uninstall completions, uninstall-completions  Uninstalls completions from your shell
  update                                        Update scala-cli - only works when installed by the installation script

Doctor commands:
  doctor  Print details about this application

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                        When called as 'scala', allow to use power commands too

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

[lwronski]

LGTM