Global marine regions datasources

[twelch]

We already publish eez-with-land and osm land datasources, but not in a centrally managed place that can be more easily maintained. This project could take that on. Once we've published datasources here, all projects start using them:

preprocessing and geoprocessing functions
in combination with geographies.
fetch features in scripts to create new datasources. For example, buffering the land polygons datasets to produce a custom marine boundary for a given country (e.g. 5 nautical miles).
These are things we often have to do manully as a one-off in each project.

Datasources to start with:

• eez-mr-v11 - Maritime boundaries v11 - world EEZ - https://marineregions.org/downloads.php
• eez-with-land-mr-v3 - Marine and land zones - union of world country boundaries and EEZ's - https://marineregions.org/downloads.php
• eez-12nm-mr-v3 World 12 nautical miles zone - https://marineregions.org/downloads.php
• land-mr - marine regions land boundaries. Not directly published but can derive by subtracting mr-eez from mr-eez-with-land
• land-osm - OSM land - https://osmdata.openstreetmap.de/data/land-polygons.html

Requirements:

• publish each datasource as flatgeobuf using import:data.
• Include crosswalk ID's such as MRGID and MRGID_EEZ in mr datasets
• include metadata for each datasource in datasources.json with version number, publish date, etc.
• potentially publish subdivided versions of each polygon datasource. Document any parameters used for the bundle step, etc.

Incorporating precalculating stats for these datasets can be an add-on task.