LGD-Ontop improvements

[ghxiao]

This PR contains several improvements of LGD-Ontop:

• Prefixes are now aligned with the Sparqify setup
• Ontop docker image is switched to the :geof tag which supports GeoSPARQL
• docker-compose.dev.yml is added to ease the development, which enables debug output and added a pgadmin container
• lgd.portal.toml file as an example to provide example queries in the SPARQL
• GeoSPARQL and other ontologies and are now imported into the LGD ontology, so that this is more modular
• Mappings are compressed by using 'meta mapping' like lgd:node{node_id} a <{object}> . This is still WIP

[Aklakan]

Thanks alot for the contribution :+1: