fix(auth status): better output for auth status

Description

Improvements to glab auth status to make it less confusing for the user:

• gives a warning when a user has a token set via an env variable (1password plugin uses an env variable)
• improve error messages
• oauth tokens no longer get flagged as invalid

Related Issues

Resolves # #1275 (closed)

How has this been tested?

Scenario	Change	Screenshot
With env var set	new warning
Oauth token	Now not displayed as invalid
Invalid token in config	now says in configuration file
No token in config	now says in configuration file

Invalid token set as env variable (multiple instances)

In the above examples i am using an oauth token for gitlab, which now isn't flagged as invalid.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap