Add functional tests for ignoring external origins

[daun]

Description

• Make sure we don't miss any regressions regarding ignoring external origins
• Inspired by issue [Bug]: External links are not being properly ignored on hover #118
• Add a url argument to page:preload hook to know what's being preloaded before the preload promise resolves

Checks

• The PR is submitted to the master branch
• The code was linted before pushing (npm run lint)
• All tests are passing (npm run test)
• New or updated tests are included

[github-actions]

Playwright test results

 76 passed
 4 skipped

Details

 80 tests across 8 suites
 1 minute, 12 seconds
 aeb3e58

Skipped tests

chromium → preload-plugin.spec.ts → active links → preloads links on touchstart
firefox → preload-plugin.spec.ts → active links → preloads links on touchstart
webkit → preload-plugin.spec.ts → active links → preloads links on touchstart
ios → preload-plugin.spec.ts → active links → preloads links on hover

[hirasso]

Very nice 🍰