OPSK-35 - link assays directly to the suggested assay and tech type

doing so through the schema rather than a fake URI. The assay URI for the
tech and assay type is now set to the correct one from the ontology
OPSK-35 drop label for assay and tech type from assay

derive it form the suggested type or ontology uri if no suggested type
(the label was only present to allow new types to be defined, before suggested types were added)
OPSK-35 updated the assay and tech type links to include the suggested term

since we will no be able to rely on the URI
OPSK-35 link suggested type to their parent using the id rather than URI

and use the parent_uri to link to the ontology if there is no suggested parent
OPSK-35 remove URI field from suggested types
OPSK-35 rename parent_uri to ontology_uri for clarity
OPSK-35 getting things back to working again

focussing on fixing tests, omitting those that are failing due to a difference in the children
or hierachy.