Make a completely new REAT API between MMLS and MMLC #57

Make a completely new REAT API (specification) for communication between MMLS and MMLC.

At the moment we have a inconsistent mix of a REST and GraphQl API for communication between MMLS and MMLC. But the GraphQl API is more like a fake GraphQl API. Therefore I think its easier to specify, implement and to use a new REST API as a new GraphQl API.