Add macro for assembling message header for use in defining tables that contain messages

[skliper]

Is your feature request related to a problem? Please describe.
Without a macro, tables are header implementation specific with their current approach of just using a uint16 array and hard coding the elements.

Describe the solution you'd like
Add an overridable macro that will fill in the header elements from "common" inputs. Something like:
#define MSG_STATIC_CMD(mid, size, fc, cksum)

Describe alternatives you've considered
None

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC