Write parser OSC > FGB

[kamicut]

Write now we parse OSC files into json using osm-adiff-parser, then geojson using real-changesets-parser and then roll up the files into one geojson and use Ogr2Ogr to create an FGB for each time resolution.

To avoid the intermediary steps, it would be interesting to build a Rust parser that reads in OSC XML and automatically packs features into FGBs. We could use FGBwriter and Geozero on the write side, but we would still need to implement adiff-parser using a custom XML to Feature parser.