DS_AppProcessCmd - cyclomatic complexity of 20

[chillfig]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I reviewed the README file to see if the feature is in the major future work.
• I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
NASA guidelines in NPR 7150.2D recommends maintaining a cyclomatic complexity in software, in particular flight software of 15. ds_app.c::DS_ProcessCmd unnecessarily violates the recommendation with a cyclomatic complexity of 20.

Describe the solution you'd like
Clean up DS_ProcessCmd such that it has a cyclomatic complexity of 15 or less.

Describe alternatives you've considered
N/A

Additional context
N/A

Requester Info
Justin Figueroa, Vantage Systems

[chillfig]

This is desired implementation of command handlers. The switch statements in question are maximally simplistic as they represent each DS command. Function is very readable and to update would likely incur more risk or make less readable.