Add `role_types` section to JSON migrations
In the course of #466 (closed) also role types got view configs. So in a declarative migration a new section role_types
is needed for role type creation.
Note: before 5.2 in a declarative migration role types were created as generic topics (in the topics
section). With 5.2 this will no longer work resp. the role type will miss its view config topic then (and, as a consequence, the detail panel's Config tab will be disabled).