Add code to manually change preferred names concepts

[lieke89]

It's possible to add custom concepts via custom_concepts.csv. dutch-umls_to_concept-table.ipynb will add these concepts to the UMLS table. After adding these terms, it's possible that there are 2 (or more) concepts with term type P. Concept names are ordered in alphabetical order. MedCAT will consider the first P term as preferred name to generate the cdb file. This might not be the term manually added in custom_concepts.csv.

Therefore we should add some code to dutch-umls_to_concept-table.ipynb to change the term type of the old preferred name into an A and the new preferred name to a P. At the moment we could do this by manually changing the UMLS file after it's generated.