Create project extended tables

First draft for project extended tables.

• Supporting concepts are not included in the changes
• All project specific core concepts and all SPHN core concepts which get influenced by the project schema are defined in tables with prefix PROJECT_EXTENDED__
• The creation of these tables is activated if the flag project_extended_tables is enabled.
• If that's the case, RML generator is run twice, one for project+SPHN schema and once for SPHN schema only.
• When extracting the data from the database we use the project extended tables as reference for the final JSON structure and in case the project extended table defines some target concepts on a property and there is only one target concept that points to an SPHN Concept, then we need to report the same target concept in the SPHN only table extraction where it won't be there.
• TODO: currently, project extended tables are created also for special concepts like DataProvider, SubjectPseudoIdentifier, DataRelease. In principle these concepts should not be touched but if they are it could create issues in the internal SPHN Connector logic. We need to decide if we want to exclude those concepts from the project extended tables. This means that we always report these tables as they are defined in the project+SPHN only schema combination. What's your opinion on that?
• The extraction logic works on simple data but I cannot assure that it will work on all edge cases. Therefore as suggested I would release this feature as a test feature that can be activated and tested.

Lucid:

SPO: spo2.sql