As per the migration plan shared last year, this migrates all browser-based tests in WordPress core to use Playwright.
This includes end-to-end, performance, and visual regression tests.
Props swissspidy, mamaduka, kevin940726, bartkalisz, desrosj, adamsilverstein.
Fixes#59517.
git-svn-id: https://develop.svn.wordpress.org/trunk@56926 602fd350-edb4-49c9-b593-d223f7449a82