fix(RDF): Output not always as expected when using table inheritance

What are the main changes you did:

Test that validated table inheritance in different ways re-used the same handler. This caused a bugged test to succeed while it should have failed as an API call with a rowId never describes the table/columns: https://github.com/molgenis/molgenis-emx2/blob/23306db3bd38b07aef7e6cf9f60a4d98241cac38/backend/molgenis-emx2-rdf/src/main/java/org/molgenis/emx2/rdf/RDFService.java#L201-L204
When filtering on table, fields belonging to child tables were not included in the RDF output. If filtering by row includes the child table data, filtering on the table as a whole should include these as well so behaviour seems more coherent.

how to test:

known issues:

When using cross-schema table inheritance, only data from the selected schemas is shown. If using a table filter, only data is shown from the table and it's children. As one cannot yet use a table filter with multiple schema's, it's impossible to only show the table with it's cross-schema children (though RDFService should support this behaviour).

molgenis / molgenis-emx2