Setting a single tab aside

[AmineI]

This PR reopens #68, which implements #63

I've done the backend code, and tested that it worked through the chrome devtools console for now. I'm not sure how add it to the context menu yet so I'll look into it later. I also believe it would be better to release 2.0 without this PR for now.

PR Checklist

• [x] Backend code for the ability to set a single tab aside
• [x] Add Context Menu item exposing this command

Localization Checklist :

• [ ] RU
• [ ] IT
• [ ] PT_BR
• [ ] ES
• [ ] ZH_CN

[AmineI]

The feature is done and working as described in #63 - it would be great if you could help with the translations on this one :) !