Make the browser extension official for Safari (at least on macOS)

**What problem does this solve?**
Since we've had Chrome and Firefox extensions for a little while now and I believe an Edge one is on the near horizon, Safari is probably the only important holdout.

I'm talking about macOS, and can test on that platform. But the same extension might be usable on iPhone and iPad, which I won't be able to test.

**Proposed Solution**
Apparently though not directly compatible with any of the other browsers, I've read that it's still quite close. I haven't actually ever tried working on a Safari extension though.

**Component**
- [ ] Core engine
- [x] Plugin/Extension
- [ ] Other: _____

**Additional Context**
Any other relevant info.