feat(auth): implement all authentication related commands

[noetarbouriech]

Changes

• Implement function Login() which sends a login request to the PaaSTech API.
• Add a test for the Login() function with a mockup server.
• Add the possibility for users to choose a custom PaaSTech server URL to log into (for testing purposes for example).
• Add configuration management using viper and the following config source:
  • ~/.config/paastech/auth.yaml - Storage for user JWT and server url.
• Add an internal/ directory for internal packages not meant to be imported by third parties.
• Add a config package which is a helper for managing config files and variables.
• Implement the following commands:
  • paastech login
  • paastech account
  • paastech logout

Notes

In order to test these changes, you need to have the API running locally and you need to add the following argument to your login command --server http://localhost:3000.
Also, building the app for testing is preferred as it gives better performances and removes useless output present when the program handles errors.

[mfernd]

🐀