SB functional test - exercise CFE_SB_ReceiveBuffer CFE_SB_PEND_FOREVER and CFE_SB_POLL options

[skliper]

Is your feature request related to a problem? Please describe.
SB functional test only calls CFE_SB_ReceiveBuffer with a timeout of 100, requirements include poll and pend forever.

Describe the solution you'd like
Exercise CFE_SB_POLL and CFE_SB_PEND_FOREVER options.

Describe alternatives you've considered
None

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC

[jphickey]

I actually added a couple calls to ReceiveBuffer w/CFE_SB_POLL as part of #1812.

I can add a call w/CFE_SB_PEND_FOREVER - didn't do this at first because if the queue is empty, that would hang the test, but that would also be a failure so probably ok? Obviously won't be able to test the case of PEND_FOREVER + empty queue....

[skliper]

Great! Please add a PEND_FOREVER call with a message on the bus so it returns immediately, no need for a test that actually pends forever. It'd also be good for the final test where it does pend for a short timeout to actually confirm at least a minimum amount of time passed.