Enable Elastic Search

Closes #276 #275

Additional implementations:

• Frontend Semantic search (units, concepts) completely overhauled, allow URIs and retrieve label in Semantic Service
• Reworked interfaces of list tables, list queries, list views and fixed PID interface (add license for DBs again)
• Reduced number of loading data from backend drastically
• Gitlab CI/CD coverage reports for Metadata Service
• Various Frontend bugs (glitching, loading)