Include SAML and sendmail support in the Review Board 5 docker image.
Review Request #12657 — Created Sept. 30, 2022 and submitted
This adds the necessary packages to build and install support for SAML
by default, and also includes sendmail. This will help users who are
currently needing to install either of these, wrapping our Dockerfile.
Successfully built new images. Verified that SAML was an option I could
try to configure.