feature: convert GeozeroDatasource to geo package

[michaelkirk]

I see there is some support for encoding/decoding geometry with geo-package: https://github.com/georust/geozero/blob/master/geozero/src/gpkg/geopackage.rs

How about a one-shot conversion of a GeozeroDatasource to convert geometry and feature data to geo package format?

let mut filein = BufReader::new(File::open("countries.fgb")?);
let mut fgb = FgbReader::open(&mut filein)?.select_all()?;
fgb.write_gpkg("contries.gpkg").unwrap();

[pka]

Would definitely be nice to have. It requires more than WKB encoding, which is already available. You have to issue SQL statements for creating tables and inserting properties together with the geometry. And the code should be similar for PostGIS output.

Example for property+geometry insertion:

geozero/geozero/tests/postgis.rs

Lines 215 to 220 in 4ec8eba

	// Insert geometry
	let geom: geo_types::Geometry<f64> = geo::Point::new(10.0, 20.0).into();
	let inserted = sqlx::query(
	"INSERT INTO point2d (datetimefield, geom) VALUES(now(), ST_SetSRID($1,4326))",
	)
	.bind(wkb::Encode(geom))