PXD-1200 ⁃ generate graphql interfaces to support querying the dictioanry

[philloooo]

users would like to query all the node types that have a certain category. 

We should generate a node type interface that has all the fields in the dictionary. Querying it will result in querying the "dictionary.schema" dict instead of the database.

example query:

_node_type (category: "biospecimen", first: 1)
{
  id
  title
}  

example result:

{
  "data": {
    "_node_type": [
      {
         "id": "sample",
         "title": "Sample"
      }
    ]
  }
}