Add option to clip floating groups to viewport

**Is your feature request related to a problem? Please describe.**
When I have a floating group, I want to move the extents beyond the element passed to `createDockview` but I want any extents beyond that element to be clipped, similarly to child windows in a Windows MDI application.

**Describe the solution you'd like**
Could be DockviewComponentOptions.clipFloatingGroupsToViewport