Update the api specification regarding the mutations `DataAccessRights`

[christoph-maurer]

[simonwacker]

Data access policies are a concept of the reference implementation of a product-data database. It is not needed for the metabase to communicate with a connected product-data database and therefore it is not part of ./apis/database.graphql (and also not of ./apis/metabase.graphql). The GraphQL schema of the reference implementation can be found at https://github.com/building-envelope-data/database/blob/develop/frontend/type-defs.graphqls and does not belong in the api project.