Add check for command APID when command queue defined

[SpaceSteve121]

The segfault in issue #42 was caused by specifying a command MID with a message not defined as a command (and which thus had no queue defined for it). The ECI code blindly attempted to utilize the queue which didn't exist, causing the segfault.

During the course of resolving that issue it was determined that a check can be done here to confirm the that there's a queue allocated if the MID indicates the message is a command.

That check would look something like if MsgRcv[idx].MsgStruct->qptr == NULL, issue an error event message warning the user about a misconfiguration, and either

• skip the configuration of the queue for that message (if we can establish that the app will still work without it)
• exit the app, if its going to be too broken to function

Work needs to be done to determine the correct course of action and implement this check.

[SpaceSteve121]

@BaldBeacon Can you take a look at this when you have time?

[SpaceSteve121]

work started in 44-add_cmd_apid_check