[Feature Request]: A new visualisation plugin type

### What would you like to happen?

For pipelines and workflows it would be nice to be able to create new plugins.
One such plugin type could be a new note type with standardized colors.
In a project you could then create 3 instances of the "new note" type: red, orange and grey background. This would be, for example, for Danger (red), Warning (orange) or standard.

In the XML serialization of the pipeline and workflow metadata we'd need the ability to add new elements that reference this metadata. Something like
* Type: NewNote
* Location: (150, 150)
* Text

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui

No file, test, or entry point is named. Start by locating the Hop GUI plugin architecture and the XML serialization for pipeline and workflow metadata; determine how a new note type and its color instances would be represented. Done should include a defined plugin and metadata format that supports the proposed note type.

Written by the indexing model from the issue text.