sc-235696/add viper

[dbolson]

Adds viper to control option flags. We can use it to eventually support env vars and a config file. The next step is to add the go API client that uses the accessToken option to make a call to get projects.

Output from running go run main.go --help

LaunchDarkly CLI to control your feature flags

Usage:
  ld-cli [command]

Available Commands:
  completion  Generate the autocompletion script for the specified shell
  hello       A hello world command.
  help        Help about any command
  setup       Setup guide to create your first feature flag

Flags:
  -t, --accessToken string   LaunchDarkly personal access token with write-level access.
  -u, --baseUri string       LaunchDarkly base URI. (default "http://localhost:3000")
  -h, --help                 help for ld-cli

Use "ld-cli [command] --help" for more information about a command.

Output from running go run main.go hello --help

A hello world command that prints out {"hello": "world"}

Usage:
  ld-cli hello [flags]

Flags:
  -h, --help       help for hello
  -i, --informal   Make the greeting less formal

Global Flags:
  -t, --accessToken string   LaunchDarkly personal access token with write-level access.
  -u, --baseUri string       LaunchDarkly base URI. (default "http://localhost:3000")

[shortcut-integration]

This pull request has been linked to Shortcut Story #235696: create command to list existing projects.

[dbolson]

I think we're going to want this pattern to eventually pass in dependencies. I'd like to move away from a global viper variable since it's implicit state, but it's easier to leave it as-is for now.

[dbolson]

We can keep the command-specific stuff in the constructor so we don't need to do this all in the root command.

[k3llymariee]

💯