Add WGRIB variable to grib-util module

[AlexanderRichert-NOAA]

Summary

This PR adds a variable WGRIB for the wgrib executable in the grib-util module.

Testing

Tested on personal machine

Applications affected

UPP, Global Workflow, EMC verif

Systems affected

all

Dependencies

none

Issue(s) addressed

#1097

Checklist

• This PR addresses one issue/problem/enhancement, or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.

[climbfuji]

@AlexanderRichert-NOAA Ready for review?

[climbfuji]

This needs to be back-ported to 1.5.1 and 1.6.0 on all systems (module generation only)

[climbfuji]

@AlexanderRichert-NOAA This PR still says "testing in progress" - has this been done? @DavidHuber-NOAA mentioned in the last meeting that this needs to be rolled into 1.5.1 and 1.6.0. Thanks!

[AlexanderRichert-NOAA]

Yes this is good to go, let me know if you want me to do some of the backporting.

[climbfuji]

I think we need the usual list of platforms and then work with @RatkoVasic-NOAA and @srherbener to make the one-line change (manually I suggest) in the env common config for 1.5.1 and 1.6.0?