Allow 'recently closed tabs' to be a panel in addition to a sub-panel, like the other sub-panels

[RenegadeScooter]

Description

I find it odd that the bookmarks, history, and sync sub-panels can also be panels (and even live only in the navigation bar), but the 'recently closed tabs' sub-panel can't.

If I want to use 'recently closed tabs', I have to keep it at the bottom of the sidebar as a button that takes up as much space as a tab. I think it would be more intuitive (and space efficient) if I was able to keep it in the navigation bar as a panel instead, just like the other sub-panels.