[ feature ] Consider replacing the multi column layout with single column + scrollbar

[JorgeR81]

I believe there are many reasons for this:

• Multi column seems to create more bugs: https://github.com/chrisgoringe/cg-controller/issues/125 https://github.com/chrisgoringe/cg-controller/issues/132

• Even when it works correctly, it's annoying to use ( e.g., if a 2nd, full size, column is created just to fit 1 extra node ). I would rather have a single column with scrollbar. It would be less invasive.

• The scrollbar would be very easy to use. People are used to it. We could use Controller mouseover + scroll wheel, to quickly access all the panels. The ComfyUI new Sidebar, also works like this.

• The scroll bar would just be a last resort. Most of the time it will not be necessary. Fitting all nodes in a single column is now easier, with the group selection and collapsible panels.

• The All Groups view would be more usable in large workflows. If we have many control nodes, in many different groups, we can fit all nodes in one column, per group. But the All Groups view will create 4 or 5 columns, and it will hide the graph canvas. 

• It's confusing having nodes changing position between multiple columns.  I'd love to use multiple columns, but only if the columns were independent ( e.g., 1 group per column  ) See here: https://github.com/chrisgoringe/cg-controller/issues/123

[chrisgoringe]

I think this is worth the experiment. I will create a separate branch today.