The nightly playwright tests are currently failing because of a
mismatch between the expected version of Chromium and what's in the
container image. Unfortunately the previous specific tag we were using
for the container image is no longer tagged on the registry. With some
testing, I was able to find an image tag that results in a good run.
Scripts for running playwright tests in a Docker container that has
chromium and webkit preinstalled. Includes a basic smoke test for
authentication so that we can be sure the test rig is working
end-to-end. Wiring this up in CI will be in an upcoming PR.