Tab Hiding & more

[JVariance]

Hi,
I like your addon more than 'Firefox Multi-Account Containers' because I stay logged in on all webpages.

1. Firefox offers an API for hiding tabs now without discarding them.
   See here: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/hide

2. It would be nice, if one would switch to the next open workspace if the last tab of the current workspace is closed instead of seeing Firefox closing completely.

3. The Addon icon is hard to see when a dark theme is used in Firefox.

4. A dark theme would be great for the addon.

5. Let us change the shortcuts