gdal raster pixel-info: add --coordinate-dataset and --output arguments

[rouault]

CC @dbaston @geographika

[coveralls]

coverage: 71.674% (+0.001%) from 71.673%
when pulling 159997c on rouault:pixel_info_input_output_vector_dataset
into 13d08a3 on OSGeo:master.

[jratike80]

What if the raster has a CRS but user wants to get pixel values from a bunch of pixels as column,line pairs? I think that option like --position-crs=none would work for that use case, but is it supported? Or does the existing --position-crs pixel https://gdal.org/en/stable/programs/gdal_raster_pixel_info.html#cmdoption-position-crs work also with a dataset input?
I see that CRS values "null" or "none" are supported in https://gdal.org/en/stable/programs/gdal_raster_edit.html#cmdoption-crs, but can they be used in other utilities?

[rouault]

What if the raster has a CRS but user wants to get pixel values from a bunch of pixels as column,line pairs?

specify --position-crs=pixel. I've added a unit test for that scenario

[geographika]

@rouault - great work!

One question, in the example:

gdal raster pixel-info --coordinate-dataset input.gpkg --input byte.tif --output output.gpkg

Does output.gpkg contain all the fields of features in input.gpkg? Being able to link raster values (e.g. DEM values to point locations) is an important use case (apologies I've not had a chance to build / test this PR).

For future reference, this new feature replaces a more convulted way of applying values from a raster to vector features:

export OGR_SQLITE_ALLOW_EXTERNAL_ACCESS="YES"
gdal vector sql points.gpkg \
    points-dem.gpkg \
    --sql "SELECT *, gdal_get_pixel_value('./dem.tif', 1, 'georef', ST_X(geometry), ST_Y(geometry)) as pixel FROM points" \
    --dialect SQLITE \
    --overwrite

[rouault]

Does output.gpkg contain all the fields of features in input.gpkg?

yes it does. Documentation updated to mention that