Offer to open a workspace from empty explorer

The empty explorer currently looks like this:  I see how we want to save space and not show a "Open Workspace" button below the "Open Folder" button, but I think we could maybe leverage @sandy081 work and show a button with a dropdown? The way this could work is: * if you just click the button it is as today "Open Folder" * if you click the dropdown next to it, you can also pick "Open Workspace" If we go down this path I would think the wording should also be tweaked ("You have not yet opened a folder or workspace"). The UI component I am referring to is this: