Investigate database schema design of the "inheritance" structure of AIAsset/AIResource

[PGijsbers]

During the Hugging Face migration, I noticed that (at least on the test server) delete operations take very long. Multiple seconds. We should investigate why this is. I assume it's a combination of the generic tables (airesource/aiasset) combined with copious delete triggers. Based on results of the investigation we may want to alter the schema, for example by introducing different many-to-many tables for different assets, instead of having a single one that's mixed.