Convert Counter Block to WYSIWYG. 

Tasks:
- Convert the LayoutSelector to a set of Block Styles (see: https://github.com/Automattic/gutenberg-block-styles) Use same thumbnail image

• Convert Title and Description to RichText components.  already existing PR
• Move Completed, Target, Text and API URL to the sidebar.
  - Refactor rendering according to PLANET-4793.

Details, references and screenshots in the document:

https://docs.google.com/document/d/1RB4mOYWzUZM7uWYcyllfSdIGCQat4n04nrsFXLGIPBE/edit#heading=h.xtmpy6dmx9j3

There is a (possibly outdated) example PR here: https://github.com/greenpeace/planet4-plugin-gutenberg-blocks/pull/73