SWOT Gravimetry data

I'd like to propose replacing the current @earth_faa dataset served with the new SWOT-based gravity grid released by David Sandwell.
The new grid (grav_SWOT_03.nc) is now available from the [TOPEX FTP](https://topex.ucsd.edu/pub/global_grav_1min_SWOT/?C=M;O=D), and David confirmed via email that we should indeed replace the old dataset with this one.

I can do it. The only issue is that there is no source grid to update the [FAA Uncertainty](https://www.generic-mapping-tools.org/remote-datasets/earth-faaerror.html). So I should ask David for that grid or remove that dataset from GMT Remote Data sets. I would choose to remove it.