Support passing github credentials if remote repository requires authentication

[awangc]

Is your feature request related to a problem? Please describe.
I'm trying to use weaver's -r option to point to a repository that is hosted on github.com but via an enterprise account requiring authentication. When generating artifacts it prompts for username and password, which prevents the tool from being used in automation pipeline directly (needs to wrap it around something like tmux)

Describe the solution you'd like
a way to pass credentials (username and password) so repositories can be accessed: specific environment variables or CLI args would be good

Describe alternatives you've considered
I've tried authenticating via gh auth login, adding git config credential.helper , setting GITHUB_TOKEN env var, but i still run into the prompt

Wrapping the weaver command around tmux works.

tmux new-session -d -s "weaver" "weaver registry generate -r https://github.com/<path-to-repository> ..."
tmux send-key -t weaver: $GHEC_USER "Enter"
tmux send-key -t weaver: $GHEC_PASS "Enter"

But this feels an extra step that could be removed.