GraphQL 4: JSON object type should be core

[unclecheese]

silverstripe-elemental uses an "ObjectType" to handle their denormalised blockSchema field for arbitrary JSON. Seems like a pretty common need, and we should just build this into the global schema, as something more specific, like JSONType.

[sirtoobii]

@unclecheese I think this issue can be closed as JSONBlob is defined here:

silverstripe-graphql/_config/schema-global.yml

Lines 8 to 11 in dce7e55

	JSONBlob:
	serialiser: 'SilverStripe\GraphQL\Schema\Resolver\JSONResolver::serialise'
	valueParser: 'SilverStripe\GraphQL\Schema\Resolver\JSONResolver::parseValue'
	literalParser: 'SilverStripe\GraphQL\Schema\Resolver\JSONResolver::parseLiteral'

[unclecheese]

Correct