Add Mapbox Styles for XYZ rasters

[roblabs]

Commit https://github.com/roblabs/xyz-raster-sources/commit/2bcc871d43fb8404fab6d0a280d331b05c5e5e77 adds Mapbox styles for some of the XYZ rasters.

See the full list at roblabs/xyz-raster-sources/styles, or you can use these hosted styles in your application.

• https://raw.githubusercontent.com/roblabs/xyz-raster-sources/master/styles/naturalearthtiles.json
• https://raw.githubusercontent.com/roblabs/xyz-raster-sources/master/styles/tileservice-charts-noaa-gov.json
• https://raw.githubusercontent.com/roblabs/xyz-raster-sources/master/styles/arcgis-world-imagery.json
• https://raw.githubusercontent.com/roblabs/xyz-raster-sources/master/styles/mapbox-satellite.json
• https://raw.githubusercontent.com/roblabs/xyz-raster-sources/master/styles/stamen-multi-rasters.json

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