Getting started guide does not cover playwright installation for running tests

[jmccullough-ithaka]

The getting started guide does not mention that installing playwright via

npx playwright install

is necessary for the test suite to run properly. The yarn test command will fail without running any tests, and an error message will appear saying the user should run yarn playwright install to install playwright - but that does not work in this repo setup. This causes confusion with how to resolve the issue.