Secure context support in Safari 15+

[Finesse]

Desktop Safari versions 15 and newer is the only browser where the Broyster Karma plugin can't run tests in secure (a.k.a. HTTPS) context.

It happens because of 2 things:

1. Safari 15+ doesn't want to ignore incorrect SSL certificates (link 1, link 2).
2. BrowserStack forces bs-local.com instead of localhost when BrowserStack Local is used and the browser is launched using Selenium, and provides no SSL certificate for bs-local.com. Unfortunately, the BrowserStack support doesn't help solving this. A related discussion: add test #14 (comment).

If any of the 2 is solved, the issue is solved. This is an ideal solution.

If they are impossible, the other option is making a custom localhost tunnel that supports HTTPS. It will be harder to use because it involves other parties.

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When this is solved, this test should be adjusted to check for secure context in all Safari versions.