adding GCAS converter

[mer-a-o]

Description

This PR adds a converter for GCAS data from the STAQS field campaign. The converter takes two option for -c or --column: total and tropo.For total, aircraft_p is set to 0. For tropo, aircraft_p is read from the obs file.

It also adds the ability to give a time range to icartt data.

Issue(s) addressed

Dependencies

None

Impact

None

Checklist

• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have run the unit tests before creating the PR

[weiwilliam]

@mer-a-o The ioda-validate.x complains following,

  Variable MetaData/aircraft_pressure
   ERROR: Variable 'MetaData/aircraft_pressure' is not listed in the YAML conventions file.
  Variable MetaData/aircraft_altitude
   ERROR: Variable 'MetaData/aircraft_altitude' uses a superseded name. Replace with 'height'
   Warning: Variable 'MetaData/aircraft_altitude' needs units, but the 'units' attribute does not exist in the file.
  Variable PreQC/nitrogendioxideColumn
   Warning: Attribute 'units' is present but is not listed as a required or optional attribute in the spec.
   ERROR: File variable 'PreQC/nitrogendioxideColumn' has units of 'unitless', which are invalid.

Multiple lines are failed to coding norm. I can fix those lines if it is fine with you.

[mer-a-o]

@weiwilliam, thanks for the review. The problem with ioda-validate.x can be addressed in a separate issue. Most compo converters use units like "unitless" or "mol mol-1". We can fix these errors and warnings once we decide on the best naming conventions for compo variables.

[BenjaminRuston]

@mer-a-o the input file is 3Mb a bit large anyway to chop it down you know of?

[mer-a-o]

@BenjaminRuston thanks for the review. The new file is now 226K.