Create a portolan index to fiboa-data datasets

[ivorbosloper]

We should publish our data in a more accessible version. Currently, we have show maps with all fiboa-0.2 datasets and the fiboa-0.3 datasets that have hcat3 crop codes. They're also visible on source-coop at https://source.coop/fiboa/ (fiboa-0.2) and https://source.coop/fiboa/data/ (fiboa-0.3). We want to use Portolan.

Therefore we should:

• Upgrade the collection.json files to a richer format (with stac-extensions and preview images), see ftw example and Dutch BRP example with faster pmtiles
• publish a catalog.json pointing to all the fiboa-0.3 dataset collection.json
• Integrate this catalog.json in a portolan page on fiboa.org (published through this repository)
• Ideally also resort the published parquets by hilbert-curve (if not sorted properly) and republish them

[ivorbosloper]

We already have a Portolan version of the fiboa-0.2 data sets, just by inserting the catalog.json into a portolan url: https://browser.portolan-sdi.org/#/external/fiboa.org/stac/catalog.json