Add styling for fv_stations WMS layer in GeoServer init

[chrismayer]

Ensure that a custom default style is added to the station_data:fv_stations WMS layer in the GeoServer init script.

[chrismayer]

Started on this but there is an issue with publishing SLDs having an InlineContent element. See https://sourceforge.net/p/geoserver/mailman/message/37341643/ So this is on hold until a solution or workaround will be found.

[chrismayer]

Meanwhile I created a GeoServer issue: https://osgeo-org.atlassian.net/browse/GEOS-10220