Bootstrap the repo

[ChunyiLyu]

Context

Initialise the cli repo, and set it up with CI and stuff. Implement the first help command; it should look like the following

$> kratix help
CLI tool for Kratix

Usage:
  kratix [flags]
  kratix [command]

Examples:
The first step to write your promise:
    kratix init promise postgresql --group myorg.com --kind database

Available Commands:
  help        Help about any command
  init        Initialize a new project
  version     Print the kratix version

Flags:
  -h, --help                     help for kratix

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

Tasks:

• [x] Use cobra to init (following https://github.com/spf13/cobra-cli/blob/main/README.md).
• [x] Add first command to our CLI (help)
• [x] Circle CI running tests on every commit
• [x] Simple readme that covers how to run test, build, and install