[Feature Request]: Allow plugins to split parts off the canvas

### What would you like to happen?

Migration: https://issues.apache.org/jira/browse/HOP-2902

Left and right side of the pipeline and workflow canvases we should be able to create a "side-bar" with which plugins could do whatever they want.

The idea is to allow plugins to take a piece of canvas real-estate which can be collapsed.  This could work for these use-cases:

Left side: "Kettle plugins tree"
Right side: data previewing
Docked transform and action properties

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui

Start with the Hop Gui implementation of pipeline and workflow canvases and its plugin extension points. Determine how a plugin could reserve collapsible left or right canvas space for a sidebar, then verify that the design supports the listed use cases: a plugins tree, data previewing, and docked transform or action properties.

Written by the indexing model from the issue text.