First attempt at automated Playwright tests (#402)

* First attempt at automated Playwright tests

* Fix deb installation in CI

* Try again with .deb

* Try xvfb

* Fix paths

* Prepare macOS runner for UI tests

* test_artifacts

* Increase test timeout to 30s

* Add timeout

* Split out build & test stages for easier retrying

* Use a single test matrix job

* Fix testing

* Yarn install

* Install deps

* Make prep more generic

* Update build.yaml

* Update build.yaml

* Update build.yaml

.gitignore

@@ -13,3 +13,5 @@
 /.npmrc
 .vscode
 .vscode/
+/test_artifacts/
+/coverage/