Add unique indexes for refdata tables

As per discussion with GBV

• refdata_category
• refdata_value

Dev task breakdown

• New migrations for the above two fields in all implementing modules, so mod-agreements, mod-licenses, mod-service-interaction
• https://docs.liquibase.com/change-types/community/create-index.html
• Use the above link to create migrations for refdata category.desc and refdata value owner+value combined