Improve automated testing for morebits

[siddharthvp]

• [x] Migrate existing tests from QUnit to Jest. Should be simple as QUnit's assert is quite similar to Node.js assert module – so most test assertions themselves wouldn't need to be changed. However assert.true which is used quite a few times isn't there in Node.js assert.
• [x] Use snapshot testing feature of Jest for writing tests for QuickForm (and maybe Morebits.status)
• [x] Remove the existing mocking code in favour of mock-mediawiki and jest-environment-jsdom which are more reliable and complete.
• [ ] Setup integration tests for Morebits.wiki.api/page/user using playwright and docker. Jest-playwright-preset package is available to link Jest with playwright. OR look into whether jsdom can be used for this (instead of playwright).

[siddharthvp]

Some of this work was done on other twinkle-related repos and just needs to be imported in.