Support diagram-only annotation elements and links

[AlexeyMz]

• Add AnnotationElement and AnnotationLink diagram cell types representing diagram-only elements and links which exports and imports with the diagram but does not exists in the data graph:
  • Support annotation elements in SelectionActionEstablishLink and new SelectionActionAnnotate components;
  • Support annotation links in LinkActionDelete, LinkActionMoveEndpoint components.
• Display and edit annotations with new built-in templates NoteTemplate and NoteLinkTemplate which use NoteAnnotation, NoteEntity and NoteLink template components:
  • Change defaultElementTemplate to defaultElementResolver, defaultLinkTemplate to defaultLinkResolver in SharedCanvasState to support new default fallbacks.
• Add AnnotationContent and ColorVariant element template state properties to support editable annotations:
  • Support ColorVariant template state property as default fallback for non-entity elements in typeStyleResolver.
• Support user-resizable element templates with ElementSize template state property and ElementTemplate.resizable flag:
  • Resizable elements display "box with handles" in the Halo to change the size;
  • Changed element sizes are captured and restored by RestoreGeometry command;
  • Add setTemplateProperty() utility function to easily set or unset template state property.
• Add TemplateProps.onlySelected flag to use in the element templates to track if the element is the only one selected without performance penalty.
• Make Halo margin configurable via CSS property --reactodia-selection-single-box-margin.
• Highlight link path in HaloLink with --reactodia-selection-link-color color by default.
• Fix DraggableHandle to avoid using stale onDragHandle and onEndDragHandle prop values.
• Refactor various places to support annotations:
  • Extract internal DragLinkMover as a utility component to use as base for DragEditLayer and AnnotationLinkMover;
  • Add internal ContentEditablePlaintext utility component;
  • Add internal ResizableBox utility component;
• Use small subset of carbon design icons for various buttons.