Draft: Add API and unit test code generator

This MR introduces:

• a generator for the API definitions;
• a generator for the code of the API, server and client sides;
• a generator for the unit tests of the API, server and client sides;
• the removal of the API server and client code dynamic generation;
• thus, the shift of the API definitions from the Krake code to the code of the newly introduced generator;
• the removal of the RoleBindingStatus, which is not used anywhere.

Closes #303 (closed), #364 (closed)