Playwright

[pbiggar]

This switches over from testcafe to playwright. Testcafe faked a lot of things, and we needed to often wait for testcafe to support something or had to hack around it. Playwright just uses the browser directly (also, it's much faster).

As opposed to before, integration tests now:

• are much faster, running in half the time
• check more errors
• ensure that no console errors are printed
• use their own package.json in
• are reliable enough not to use retries too much
• are in typescript
• do not need the integration test hacks
• are much more stable, due to better checking of completion conditions after actions
• automatically upload the full trace in CI so you can see exactly what actually happened when the tests failed
• wait until after the fsharp-backend tests so that they can load the generated blazor

TODO:

• build and use updated dockerfile
  • remove circle.yml hack and set -x
• update the README
• move console logs into same directoy as other tests
• remove testcafePrefix thing
• latest playwright
• add output-processing test to compile/CI
• remove old integration tests
  • code
  • CI
  • rename playwright
  • package.json
• set concurrency to 2 or 3
• update prep.sh

Followups:

• move test_appdata into integration-tests
• make it work with F# server
• make it work with blazor