[raster] Make a ST_Extent(raster) aggregate taking rotation into account
|Reported by:||pracine||Owned by:||pracine|
Right now we can use ST_Extent(rast::geometry) to get the non rotated extent of a set of rasters but we might want to get the rotated extend instead.
This aggregate should be based on a _st_extent(raster, raster) doing basically the samething as ST_MapAlgebra(,'UNION') when it precompute the size of the resulting raster.
This could then be used by the GDAL driver or any process needing to precalculate the size of a coverage before burning tiles in it.