Library of Blocks: ensure consistency in patterns used

[mtias]

As we approach release and merge windows, we need to make sure our core blocks are written in the way we want other blocks to be written. That means consistent expression (i.e. array of return values in edit functions, accessing globals vs imports, CSS scope and classes, declaration of toolbar controls, etc).

[youknowriad]

@mtias Should we close this issue? It's not an actionable item