SWY tests do not test raster outputs

[dcdenu4]

When working on #1541 , I thought I would add a test for QF.tif, but realized that there was no real regression testing happening for rasters anywhere. It instead does some vector aggregate testing for regression tests. Since a lot of functions have been moved to pgp.raster_map or the like for simplification, this means unit tests aren't really picking up on these either. So we end up with limited ability to know when introduced changes cause a bug in the raster outputs.

SWY should have better regression tests for raster outputs.