add eurobis_occurrences_grid

[salvafern]

Previous version had getOccurrencesGrid().
To look into adding this layer in the new version too.

Ideally also:

• add leaflet map that displays the occurrences with WMS.
• option to convert into raster? or explain how in a vignette?

[salvafern]

These approaches work: the first one works fine, the second is not filtering fine but returns a grid. Something must be wrong about the filter.

library(magrittr)
test <- eurobis:::eurobis_base_map() %>%
  leaflet.extras2::addWMS(
    baseUrl = "http://geo.vliz.be/geoserver/Eurobis/wms?VIEWPARAMS=tablename:1d;AphiaID:495077",
    layers = "eurobis_grid",
    options = leaflet::WMSTileOptions(
      transparent = TRUE,
      format = "image/png",
      info_format = "text/html"
    ),
    attribution = shiny::HTML("<a href='https://marineregions.org/'>Marine Regions</a>") 
  )

They use different layers

library(magrittr)
test <- eurobis:::eurobis_base_map() %>%
  leaflet.extras2::addWMS(
    baseUrl = "http://geo.vliz.be/geoserver/Dataportal/wms?VIEWPARAMS=where:dasid=8045",
    layers = "eurobis_grid_1d-obisenv",
    
    options = leaflet::WMSTileOptions(
      transparent = TRUE,
      format = "image/png",
      info_format = "text/html"
    )
  )

I am not sure this is a feature that we need in the package. I would not put more time in this and only pick up again if we get some requests.