SCORU: Special encoding for internal operations

Internal operations are now encoded as external ones. We might need to use a different encoding scheme if we extend the types.

Solving the issue is done by dividing it into the following steps:

• !5381 (merged): some preparatory work, where things are copied, moved or deleted, so that it is more apparent what is used for external or internal operation results;
• !5384 (merged): creating and using dedicated types for internal operation results;
• !5149 (merged): moving internal operation results to a new module;
• !5737 (merged): renaming types and functions.