WIP: tests: convert core to mocha

[connorjclark]

See #14047

To run:

yarn mocha lighthouse-core/test

ref #13568
#14020 was merged into this branch too.

[connorjclark]

I've been only testing with Node 14 locally, but turns out Node 16/17 error due to some bug re: marky (which uses performance.mark) and @jest/fake-timers (which mocks process.hrtime).

It's only navigation-test.js, which I suppose explains this import at the top:

import 'lighthouse-logger'; // Needed otherwise `log.timeEnd` errors in navigation.js inexplicably.