Support loading WMTS/XYZ from links

[m-mohr]

Some collections have links like

{
  href: 'https://...',
  rel: 'wmts',
 "wmts:layer": "abc",
 "wmts:...": "..."
}

We could read those and show them. See also the implementation in the openEO Web Editor. Example Catalog: https://openeo.vito.be/openeo/1.0/

Specified in web-map-links:

• [ ] WMTS (WMTS support in Leaflet missing)
• [x] XYZ (implemented)
• [ ] TileJSON

[m-mohr]

Main issue is that there's no native WMTS support for Leaflet and that are the only real-world examples we have out there right now. Also, WMTS may include a time dimension where the name of the dimension is not pre-defined.

[m-mohr]

XYZ is supported