reload flag for "overlay new" command

[j-xella]

Related problem

If we do overlay use xxx, and then mess it up, we can get back to the beginning with overlay use -r xxx.

This does not seem to be possible for "dummy" overlays created with overlay new yyy. We can hide the overlay, but after that, overlay new yyy will just bring the hidden overlay from hiding.

Describe the solution you'd like

overlay new could have an -r flag, the same as overlay use, which would reset the overlay (to nothing).

Describe alternatives you've considered

Use new overlay with different name; or new instance of the nu shell

Additional context and details

No response