Add new output fileType .covjson

[BobSimons]

Add a new output file type to ERDDAP: Coverage JSON (.covjson) See https://covjson.org/

Talk with the covjson people to see if the project is still active and if they think it is worth the effort.

Skills required: Java programming.

Difficulty: Relatively easy. ERDDAP datasets have a cdm_data_type (featureType) attribute which aligns with the Coverage JSON types. So you just need to write the code to deal with each of the cdm_data_types. Perhaps 1 month's work (after you figure out ERDDAP).

Mentor: Bob Simons (main author of ERDDAP)

Please also read the Programmer's Guide at https://coastwatch.pfeg.noaa.gov/erddap/download/setup.html#programmersGuide especially the "Judging Your Code Contributions" section.

(Rich Signell requested this feature.)