Need a "Window -> Reset to Default Layout" action for resetting the KDDockWidget layout

[krf]

With KDDockWidgets as docking window manager you can rearrange the views freely. If you mess it up there's no easy way to get it back to the default layout. The layout is even restored on startup.

We need some "Window -> Reset to Default Layout" action or the like.

Relates to #467.

[GitMensch]

Workaround as mentioned in the issue:

[closing hotspot, then] deleting ~/.config/hotspotrc [then restart] did the trick!

Would love to have this in the menu and possibly with a keyboard shortcut assigned.