Automate authentication in build system

[JasonYeMSFT]

To tighten the security during development, we are no longer allowed to use personal access tokens that last longer than 7 days. We should seek a more automated solution for authentication in build system so we don't have to manually refresh the credentials every week. Make sure the new solution doesn't introduce new security vulnerabilities, such as opening the door for us to forget about the automated process and leaving live credentials unattended.