Replace Nightwatch testing with Playwright

Problem/Motivation

Nightwatch tests have proven to be too shaky for my liking and may not be a good long-term choice.

Details:

• Random fails, such as: https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/3888711 and https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/3888757
• Outputs errors, but tests still run normally such as: https://git.drupalcode.org/project/ckeditor5_paste_filter/-/jobs/3888793
  

      Error   Error while running .clearElementValue() protocol action: invalid element state
    (Session info: headless chrome=106.0.5249.103)
    (Driver info: chromedriver=106.0.5249.61 (511755355844955cd3e264779baf0dd38212a4d0-refs/branch-heads/5249@{#569}),platform=Linux 5.10.230-223.885.amzn2.x86_64 x86_64)
      Error   Error while running .clearElementValue() protocol action: invalid element state
    (Session info: headless chrome=106.0.5249.103)
    (Driver info: chromedriver=106.0.5249.61 (511755355844955cd3e264779baf0dd38212a4d0-refs/branch-heads/5249@{#569}),platform=Linux 5.10.230-223.885.amzn2.x86_64 x86_64)
  

• Difficulty running/maintaining tests that work across Drupal 9.5.x, 10.x, and 11.x in part due to differing Nightwatch versions

Although Drupal core uses some Nightwatch tests, we don't need to restrict ourselves to the testing tools shipped with core.

Also, Drupal core might adopt Playwright.

Proposed resolution

Replace Nightwatch with Playwright.

Remaining tasks

• Set up Playwright for testing
• Port existing tests to Playwright

User interface changes

n/a

API changes

n/a

Data model changes

n/a