Add unit tests for existing features

We developed the hackathon features without unit testing. Make sure to cover ( mostly the happy flow ) the following units:

- Github Integration ( fetching current branch for example... )
- API polling including states changes
- Notification popup when the status of the environment is changed
- Changed icons of an environment ( including approve/cancel )
- Live deployment logs
- API client tests ( axios, authentication headers )
- Reading API key from settings file

Examples of unit testing can be found widely in the marketplace ( choose an extension and go to its repo )
[Official reference](https://code.visualstudio.com/api/working-with-extensions/testing-extension)