Tim Schmitz

DataCollection: introduce LOM

4

This PR introduces LOM for `DataCollection` as described in [Learning Object Metadata for Data Collection](https://docu.ilias.de/go/wiki/wpage_8114_1357). For details on what this entails, see the [documentation](https://github.com/ILIAS-eLearning/ILIAS/blob/trunk/components/ILIAS/MetaData/docs/enabling_lom.md). It also adds an extremely bare-bones...

Test/TestQuestionPool: LOM as tail dependency in export

1

This PR replaces almost all usages of the old `MetaData` classes in `Test` and `TestQuestionPool` related to export/import. For everything else, see #7923. From what I could gather from [28891](https://mantis.ilias.de/view.php?id=28891)...