--token in GitHub provider should take precedence over GITHUB_TOKEN

[tas50]

Describe the bug
Command line flags should always come first. Right now if you set a value in the GITHUB_TOKEN env var we will use that even if you provide a CLI --token flag. This can be very confusing and resulted in this PM troubleshooting what was wrong with his token for WAY too long before realizing the mistake. Let's make sure explicit values provided with --token are authoritative.