Align metadata to DCAT/DCAT-AP

**Is your feature request related to a problem? Please describe.**
Align to DCAT metadata to describe datasets

**Describe the solution you'd like**
Reuse terms and structure from DCAT in the metadata file, ideally generate a json-ld file dcat compliant

**Describe alternatives you've considered**

**Additional context**
DCAT is a W3C standard extended in Europe with DCAT-AP, an example is data.europa.eu publishing datasets metadata in DCAT-AP