Improve the YAML schema and harmonize it across question types

All command line options except for input and output should be migrated into the YAML schema (with sensible defaults) to reduce manual effort. This especially applies to the question type.

Furthermore, the schema should be harmonized across question types. For example, there should always only be a single feedback key that, depending on the question type, needs to be mapped to different Moodle XML keys.

Some questions, like multiple_choice currently do not support feedback.