[Quality] Review and map current tables in the dataverse

There's no current database scheme of all the tables and their relationships in the dataverse.
While doing this, we must identify any data duplicity, make sure primary keys are set in the most appropriate way and identify any tables that could be removed or merged.

The goal of this issue is to ensure relational databases principles, prevent data duplicity, garbage data, and ensure tables rules. As well as to end up with a schema of the whole database we can use for future reference.

No files, tests, or entry points are named. Start by locating the current Dataverse table definitions and recording tables, relationships, primary keys, and duplicate data; done means a complete schema reference plus documented findings on keys, duplication, and tables proposed for removal or merging.

Written by the indexing model from the issue text.