Fix Channel dimension names when category empty

[rmclaren]

Summary

• ensure dimensions are created even if source data is empty

Testing

• ctest --output-on-failure (fails: No tests were found)

[emilyhcliu]

@rmclaren This fix from codex works!!

netcdf gdas.t00z.atms_n21.tm00 {
dimensions:
        Location = UNLIMITED ; // (0 currently)
        Channel = 22 ;
variables:
        int Location(Location) ;
                Location:_FillValue = 2147483647 ;
        int Channel(Channel) ;
                Channel:_FillValue = 2147483647 ;

// global attributes:
                :description = "ATMS Level-1B data processed using FFT-based beam convolution to standardize all channels to a common 3°×3° spatial resolution" ;
                :platformCommonName = "JPSS" ;
                :platformLongDescription = "Joint Polar Satellite System" ;
                :sensorCommonName = "ATMS" ;
                :sensorLongDescription = "Advanced Baseline Imager (ATMS) - 22 channels including the 54 and 183 GHz bands; cross-track scanning" ;
                :source = "U.S. National Weather Service, National Centres for Environmental Prediction (NCEP))" ;
                :sourceFiles = "NCEP BUFR Dump - atms NC021203 Normal Feed" ;
                :processingLevel = "Level-1B" ;
                :converter = "bufr-query" ;
data:

 Channel = 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ;

[rmclaren]

I noticed that as well, I wanted to take some time to look at it carefully before I declare is "the solution". It made a lot of changes. I used th github copilot agent in the last try to see how it stacks up. It's solution looked good, but didn't work... I have to be careful about just accepting the changes it recommends. I'm starting to learn to be careful with these things :)

[emilyhcliu]

I will change it back to draft