Support for OpenID Connect, keyless authentication

Hello,

please consider to introduce keyless way how to communicate with firebase.
I would really love to use this way in our GitHub repositories, Actions.

Now we have to handle, maintain several service account keys, secrets and it's real pain.

Inspiration: https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/configuring-openid-connect-in-amazon-web-services