Draft: T&A Export/Import Refactoring

[lukas-heinrich]

Hi everyone,

this PR concerns the refactoring of export/import in the Test and TestQuestionPool components.

Objective

This refactoring reintegrates the test export into the intended export process of ILIAS. In detail, the PR pursues the following objectives:

• The export works both for the current structure and after the migration to the answer types.
• A clear separation of responsibilities makes it possible to add further export options and formats in the future without having to modify the entire export process.
• The export of the Test component is migrated into the structure and interfaces of the global export component. This avoids the parallel infrastructure that previously existed.
• After integration into the ILIAS core, the previous export format will continue to be supported for at least one major version. To this end, compatibility between the previous and the new format is established.

Core idea

The export process is divided into two clearly separated responsibilities:

1. Gathering all content and metadata required for the export. This data initially exists in different forms (for example as data objects, nested array structures, or exports from other components) and is transferred into an independent, simplified structure that is decoupled from the specific export option.
2. These data structures are then converted into the respective target format and persisted in one or more files.

This separation ensures that the export can be implemented independently of the output format, so that not every exportoption needs to build its own process.

The complete concept, including more detailed explanations, is attached here:
Konzeption_ Test Export.pdf

Note: This PR is currently still in an internal review process and is not yet final. Bug fixes and cleanup work will be added incrementally. We nevertheless welcome any comments and feedback.