More open data file formats

#New

• Shapefile, GeoPackage and KML/KMZ readers for previews, thumbnails and loading, including supported files inside ZIP archives.
• Column and row sampling for GeoPackage, KML/KMZ and XLSX sources.

#Fixed

• A failed source file no longer prevents sampling another file with the same format.
• Geographic file filtering happens before the feature limit. File geometry is transformed to longitude and latitude, with limits on expanded archive size.