remove properties-as-string shorthand

[ianstormtaylor]

Do you want to request a feature or report a bug?

Debt.

What's the current behavior?

Right now you can use a type string as a shorthand for properties in many places. I'd like to remove this because it's really not harder to properly write it out as an object and I think it makes the API harder to read when the shorthand is used.

So, for example...

editor.setBlocks('paragraph')

Becomes...

editor.setBlocks({ type: 'paragraph' })

[ianstormtaylor]

Fixed by #3093.