Fix: Prioritises env var authentication over profile authentication

[cveticm]

Proposed changes

Before, if authType was already set, we would not check to see if another auth type is available, this would cause env vars to be ignored in the case:

• profile you run the command with is of different auth type to credentials you are setting with env vars

Caveat:
We still have the issue of default showing when default profile does not exist and env vars are set when running atlas config list as the auth type will be set
atlas config describe default shows that only auth tpye is set, and is set to the auth type of the credentials provided through env vars.

[coveralls]

coverage: 64.152% (-0.003%) from 64.155%
when pulling 613fe93 on chore_env_var_fix
into f5f8742 on master.