workspace: change annotation color behaviour

Description of requirement

Annotation color palette/map must be defined in apps instead of the slide-viewer itself. The slide-viewer just accepts a colormap for annotations. Provide a default colormap if no annotation rendering hint is set in the ead, otherwise use the colors of the rendering hint.

Acceptance criteria

• AC: remove color palettes from slide-viewer
• AC: add default colormap(s) to in app (should be in a lib for easier reuse)
• AC: use annotation rendering hint to set the colors