Update unit test cases to support cmd handler lookup table

[jphickey]

Is your feature request related to a problem? Please describe.
The CFE test cases currently invoke the command handler by setting up the MsgID + CC and relying on the FSW "switch" statement to call the handler.

An alternative implementation is to use a (generic) command handler lookup table, but the unit tests don't easily adapt to this model currently.

Describe the solution you'd like
Add the logic to allow setting up the stubs for lookup table dispatching.

Additional context
EDS uses generic lookup tables for message dispatching, and thus the stubs need to be configured accordingly. This can be accomplished by changing how the UT dispatch setup is configured.

Requester Info
Joseph Hickey, Vantage Systems, Inc.