Ability to run polygonize on rasterized model output

[cholmes]

The final major set of functionality, 'step 3' from #1, would be to run the ftw inference polygonize code to generate fiboa / geoparquet and other vector outputs (geojson, fgb, geopackage). And ideally to be able to select different polygonize parameters (min size, eventually max size, remove interior).

The initial sync api doesn't have an option for this, but when we support async / bulk processing it could be nice to enable users to point at a set of raster images and run different polygonize commands.

[cholmes]

This isn't a priority for the short term, as the API does all three steps in one.