Allow API key instead of username/password in Unity Command Line

As suggested in another thread, https://forum.unity.com/threads/ple...ken-environment-variable.682270/#post-4732289, I'd like to be able to pass a key into the command line instead of hard-coding the username and password into my continuous integration server configuration. This is a security risk and is frowned upon by my organisation. It would be helpful to have this option.