Schema validation should live in cms-prototype-blocks?

[jna-unikent]

It seems the right place to validate the json schema would be in the cms prototype blocks repo since the definitions live there.

It would be good for the validation to be run when stuff is committed into that repo.

Alternatively we could pull out the validation into its own repo and then pull it into both astro and cms-prototype blocks.

https://github.com/unikent/astro/blob/develop/package.json#L12

[samyapp]

Probably best to have it in both places, as its possible we may have multiple "cms-prototype-blocks" repos in the future being mixed into the main build process.