Canvasblocker: Add protection for APIs in web workers

[kkapsner]

APIs used in web workers (Worker, SharedWorker, ServiceWorker) are not protected by CanvasBlocker. They should be protected!

At the moment only the navigator API can be used in web workers but when https://bugzilla.mozilla.org/show_bug.cgi?id=1390089 lands offscreen canvas can be used to extract the canvas fingerprint.

[kkapsner]

I do not see a good way to do that at the moment. Therefore I created https://bugzilla.mozilla.org/show_bug.cgi?id=1636977 - maybe Firefox will implement something useful.

[geeknik]

I triaged the Firefox bug report for you, hopefully it gets picked up. 👍🏻

[kkapsner]

Thanks.

[Riajyuu]

maybe sth for reference
https://github.com/jingyu9575/service-worker-control

[kkapsner]

Thanks for the link. The protection approach is a little bit different so I think I have to do it different. But I may have some ideas of how to do something myself...