Allow dragging to hide the terminal tabs

[mjbvz]

Testing #122242

With the terminal tabs, I expect to be able to hide them by clicking on the sash and dragging. This similar to what we support for the sidebar and panel

[Tyriar]

This isn't particularly discoverable and it seems somewhat harmful where a user could accidentally hide the tabs this way and not know how to bring them back, plus this has a special narrow tabs view when "minimized", similar to other views:

These are less of a problem for the sidebar and panel because of the amount of ways to get it back, hiding tabs is changing a setting to say you don't want to see them anymore.