Add environment command

[endorama]

Taking example from gh cli, add an environment command that prints environment information & defaults.

gh environment

GH_TOKEN, GITHUB_TOKEN (in order of precedence): an authentication token for github.com
API requests. Setting this avoids being prompted to authenticate and takes precedence over
previously stored credentials.

GH_ENTERPRISE_TOKEN, GITHUB_ENTERPRISE_TOKEN (in order of precedence): an authentication
token for API requests to GitHub Enterprise. When setting this, also set GH_HOST.

GH_HOST: specify the GitHub hostname for commands that would otherwise assume the
"github.com" host when not in a context of an existing repository.

GH_REPO: specify the GitHub repository in the "[HOST/]OWNER/REPO" format for commands
that otherwise operate on a local repository.

GH_EDITOR, GIT_EDITOR, VISUAL, EDITOR (in order of precedence): the editor tool to use
for authoring text.

GH_BROWSER, BROWSER (in order of precedence): the web browser to use for opening links.

GH_DEBUG: set to a truthy value to enable verbose output on standard error. Set to "api"
to additionally log details of HTTP traffic.

DEBUG (deprecated): set to "1", "true", or "yes" to enable verbose output on standard
error.

GH_PAGER, PAGER (in order of precedence): a terminal paging program to send standard output
to, e.g. "less".

GLAMOUR_STYLE: the style to use for rendering Markdown. See
<https://github.com/charmbracelet/glamour#styles>

NO_COLOR: set to any value to avoid printing ANSI escape sequences for color output.

CLICOLOR: set to "0" to disable printing ANSI colors in output.

CLICOLOR_FORCE: set to a value other than "0" to keep ANSI colors in output
even when the output is piped.

GH_FORCE_TTY: set to any value to force terminal-style output even when the output is
redirected. When the value is a number, it is interpreted as the number of columns
available in the viewport. When the value is a percentage, it will be applied against
the number of columns available in the current viewport.

GH_NO_UPDATE_NOTIFIER: set to any value to disable update notifications. By default, gh
checks for new releases once every 24 hours and displays an upgrade notice on standard
error if a newer version was found.

GH_CONFIG_DIR: the directory where gh will store configuration files. If not specified, 
the default value will be one of the following paths (in order of precedence):
  - "$XDG_CONFIG_HOME/gh" (if $XDG_CONFIG_HOME is set),
  - "$AppData/GitHub CLI" (on Windows if $AppData is set), or
  - "$HOME/.config/gh".

GH_PROMPT_DISABLED: set to any value to disable interactive prompting in the terminal.

GH_PATH: set the path to the gh executable, useful for when gh can not properly determine
its own path such as in the cygwin terminal.