Update Plain_netCDF_Time to use standard MAPL error handling

[darianboggs]

Description

Make Plain_netCDF_Time (base/Plain_netCDF_Time.F90) consistent with standard MAPL error handling.

Related Issue

#2375

Motivation and Context

Using standard MAPL error handling allows better location of problems through stack traces.

How Has This Been Tested?

Ran successful 0-diff GEOSgcm runs

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)

Checklist:

• I have tested this change with a run of GEOSgcm (if non-trivial)
• I have added one of the required labels (0 diff, 0 diff trivial, 0 diff structural, non 0-diff)
• I have updated the CHANGELOG.md accordingly following the style of Keep a Changelog

[tclune]

Eventually I want to give some thought if this can/should be merged with Netcdf4_FileFormatter.

[darianboggs]

Eventually I want to give some thought if this can/should be merged with Netcdf4_FileFormatter.

I agree. The NetCDF handling should be consolidated in MAPL. There is redundancy, probably. The handling of CF units itself could be a module itself.