Fix #167, Rename CommandCode variable to FcnCode

[thnkslprpt]

Checklist

• [x] I reviewed the Contributing Guide.
• [x] I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution

• Fixes #167
  • Rename the CommandCode variable in SAMPLE_APP_ProcessGroundCommand() to FcnCode to better align with the cFE API.

Testing performed Standard cFS bundle tests all passed. Build/run cFS and test NOOP and other commands with the GroundSystem tool. All working fine.

Expected behavior changes No impact on behavior. Improves code clarity and consistency in the lab apps.

System(s) tested on Intel(R) Celeron(R) N4100 CPU @ 1.10GHz x86_64 Debian GNU/Linux 11 (bullseye) cFE v7.0.0-rc4+dev197, OSAL v6.0.0-rc4+dev143, PSP v1.6.0-rc4+d Sample App v1.3.0-rc4+dev35 CI Lab App v2.5.0-rc4+dev39 TO Lab v2.5.0-rc4+dev31

Contributor Info Avi Weiss @thnkslprpt