Fix projection units

[tdrwenski]

Description of Changes

Some NCSS requests are failing for satellite data (geostationary projection) when the x/y axes have units micro radians. This PR fixes this by moving the unit handling out of the projection class, into the HorizCoordSys class that is used by coverages. This PR contains:

• Add test
• Generalize unit handling in HorizCoordSys using the SimpleUnits to work for more than just km/m, given that a projection specifies its default unit.
• Remove/deprecate code in Geostationary related to unit handling.
• Add default unit to Geostationary and LambertConformal classes.

[tdrwenski]

Jenkins tests passing: https://jenkins-aws.unidata.ucar.edu/view/Users/job/tara-netcdf-java/25/