Add gh extensions outdated command + indicate outdated extensions in gh extensions list and similar #8327

⇒ gh extension upgrade -h
Upgrade installed extensions

USAGE
  gh extension upgrade {<name> | --all} [flags]

FLAGS
  --all       Upgrade all extensions
  --dry-run   Only display upgrades
  --force     Force upgrade extension

INHERITED FLAGS
  --help   Show help for command

LEARN MORE
  Use 'gh <command> <subcommand> --help' for more information about a command.
  Read the manual at https://cli.github.com/manual

⇒ npm outdated -h
Check for outdated packages

Usage:
npm outdated [<package-spec> ...]

Options:
[-a|--all] [--json] [-l|--long] [-p|--parseable] [-g|--global]
[-w|--workspace <workspace-name> [-w|--workspace <workspace-name> ...]]

Run "npm help outdated" for more info

    outdated: |
      !gh_extensions_outdated() {
        if [ "$1" = "-h" ] || [ "$1" = "--help" ] || [ $# -ne 0 ]; then
          echo "Usage: gh outdated"
          echo "Check for outdated GitHub CLI extensions and the gh CLI tool itself."
          echo ""
          echo "This command performs the following actions:"
          echo "  - Lists all installed gh extensions."
          echo "  - Checks if any installed extensions have updates available."
          echo "  - Offers to upgrade individual extensions if updates are available."
          echo "  - Checks if the gh CLI tool is up to date and offers to upgrade it if not."
          echo ""
          echo "Options:"
          echo "  -h, --help     Show this help message and exit."
          return 0
        fi

        gh extension list

        echo

        echo "Release notes:"
        (gh extension list | awk '{print $3}' | sed 's#^#  https://github.com/#' | sed 's#$#/releases#')

        echo

        echo "Checking for outdated extensions..."
        outdated_extensions=$(gh extension upgrade --all --dry-run)
        outdated_found=false

        while read -r line; do
          if [[ $line == *"would have upgraded from"* ]]; then
            outdated_found=true
            extension_name=$(echo "$line" | awk '{print $1}' | tr -d '[]:')
            current_version=$(echo "$line" | awk '{print $(NF-2)}')
            new_version=$(echo "$line" | awk '{print $NF}')

            echo "  Extension $extension_name is outdated (Current: $current_version, Available: $new_version)"

            # echo "Do you want to upgrade $extension_name? [y/N]"
            # read -r upgrade_extension
            # if [ "$upgrade_extension" = "y" ]; then
            #   gh extension upgrade "$extension_name"
            # fi
          fi
        done <<< "$outdated_extensions"

        if [[ $outdated_found == true ]]; then
          echo "Do you want to upgrade all outdated extensions? [y/N]"
          read -r answer
          if [ "$answer" = "y" ]; then
            gh extension upgrade --all
          fi
        else
          echo "  All extensions are up to date!"
        fi

        echo

        echo "Checking to see if gh is up to date..."
        if brew outdated gh | grep -q 'gh'; then
          echo "gh is outdated. Do you want to upgrade? [y/N]"
          read -r upgrade_gh
          if [ "$upgrade_gh" = "y" ]; then
            brew upgrade gh
          fi
        else
          echo "  gh is up to date!"
        fi
      }; gh_extensions_outdated $@

⇒ gh outdated
NAME              REPO                      VERSION
gh actions-cache  actions/gh-actions-cache  v1.0.4
gh copilot        github/gh-copilot         v0.5.3-beta

Release notes:
  https://github.com/actions/gh-actions-cache/releases
  https://github.com/github/gh-copilot/releases

Checking for outdated extensions...
  All extensions are up to date!

Checking to see if gh is up to date...
  gh is up to date!

⇒ gh outdated
NAME              REPO                      VERSION
gh actions-cache  actions/gh-actions-cache  v1.0.4
gh copilot        github/gh-copilot         v0.5.3-beta

Release notes:
  https://github.com/actions/gh-actions-cache/releases
  https://github.com/github/gh-copilot/releases

Checking for outdated extensions...
  Extension gh-copilot is outdated (Current: v0.5.3-beta, Available: v0.13.37)
Do you want to upgrade all outdated extensions? [y/N] y

# Output for the upgrade process is not shown in this example.

Checking to see if gh is up to date...
  gh is up to date!