Secrets support

[crazy-max]

User can't currently pass secrets to their build like in build-push-action and bake-action.

This should be supported but dynamic secrets are not supported by reusable workflows atm: https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#onworkflow_callsecrets

Maybe we could something similar to registry-auths secret with a YAML object but might not work for multiline secrets 😣