Replace Nightwatch testing with Playwright

More random fails:

• https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/4490782
• https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/4490484
• https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/4490807
• https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/4490815

I did a quick search today and found that core is looking to go in the direction of Playwright, which based on my recent evaluations for a client project would be very high on my list as well.

Tools to check out:

https://github.com/Lullabot/ddev-playwright
https://github.com/julienloizelet/ddev-playwright

At this point the path seems clear to use Playwright, of course things can change but converting to a task for now.

I am hoping to have some time available in the next week or two to continue this work.

Taking up work on this again.

Some notes to share, in hopes that this can be helpful to others setting up/converting Playwright in their projects, and especially those relatively or entirely new to Playwright:

• I used DDEV and https://github.com/Lullabot/ddev-playwright with kasmvnc to make use of the actual Playwright UIs.
• From what I can tell, the Lullabot Playwright DDEV add-on assumes a path of test/playwright, but I just followed their setup instructions and didn't make use of those files at any point. Arguably this should be configurable/overrideable, and I might create an issue/MR in the add-on to address this in future.
• The Playwright docs are great and I found it easy to look up the various types of assertions and such.
• In particular reading through the first few parts of https://playwright.dev/docs/test-fixtures was very helpful to better understand things.
• Code generation can be handy to get a starting point, but be prepared to refine the code that comes out of it. Also, even with VS Code, you can't really "append" to an existing test case like I was hoping. I wasn't really able to find anything satisfying here, especially since I don't normally use VS Code, but I may need to experiment with the approach described in https://github.com/microsoft/playwright/issues/28571 to see if this would be viable without VS Code. See also https://github.com/microsoft/playwright/issues/23625.
• Related to code generation, you may find it useful to run yarn playwright codegen $(drush uli --uri=http://web) (this is assuming DDEV, adjust as needed) to generate initial test code in an environment similar to the test environment. If you use test modules, add to settings.php/settings.local.php the line $settings["extension_discovery_scan_tests"] = TRUE;.
• I found it to be important that drush is available and installed in the correct location, otherwise you may get errors that are very hard to diagnose. At one point I unintentionally installed drush inside the module rather than in the site's bin, and my test module was failing to install in Drupal 11 but all I could see was that the site hadn't installed.
• I found await page.waitForTimeout(60_000); useful in conjunction with kasmvnc, at least before I learned about the built-in debugging tools available.
• Depending on what you are testing, be aware that this setup is not fully isolated, since all the workers use the same site URL. So in my experience config changes can easily bleed in between workers and cause problems. This led me to be add steps to reset config and in general trying to isolate individual test cases. In the end, I'm able to run the tests fully parallel without issue, at least with a single browser.
• In CI, sometimes the database will fail to connect on site install. This is very similar to the main issue I had with Nightwatch, but Playwright (at least as configured here) will just retry it so it's much less of an issue. I spent a short amount of time seeing if this could be fixed but didn't get too far.

Going to call this done.