Investigate and experiment on the block model v3

[sneridagh]

DLR Block model (v1)

The block has all the information needed for render itself, but the rules are exhaustive and cumbersome, prone to error if they are not exhaustive enough.

VLT Block model (v2)

After DLR experience, we tried the approach of using a block wrapper in view mode that would arrange the blocks are grouped by a property (background color) and wrapped in a container. This container is the one having the vertical spacing and the color.
This proved to simplify CSS dramatically, with the drawback that the wrapper and the arrangement logic should be present in the view mode, being very difficult to do the same in edit mode because of the DandD existing wrappers, so the edit mode renders "ugly" without them.

Layout and vertical space rules

https://github.com/kitconcept/volto-light-theme#vertical-spacing-rules
https://github.com/kitconcept/dlr-internet/blob/main/docs/development/layout-rules.md

Experimentation on a v3

The reason of this issue is the experimentation and exploring new ways to improve the v1 situation without the need of the wrapper.

Deliverables

• Diagram of the new block model
• Develop an effective and comprehensive way to:
  • How to create a new block from scratch using it
  • How to style it using the v3
  • How to override styles in a block using v3
• Tests using the Visual Regression Tool
• Documentation