New data accessor to use gbif dataset like source

[abennici]

• [x] Explore the capabilities of the existing rgbif package to request gbif datasets.
• [x] Create gbif software to put user credentials in config
• [x] Create a gbif accessor to use source gbif datasets.
• [x] Investigate about the best way to query data and reuse some entity metadata fields to invoke enriched queries.
• [x] Determine methods to unify the spatialization of the sourced data sets.
• [x] Brainstorming about adding options to offer to users (field restrictions, complete selection, images, etc.)