Add a functional test for CFE_PSP_GetCFETextSegmentInfo

[skliper]

Is your feature request related to a problem? Please describe.
Related to #111 - really need functional tests for all the APIs, but there was a bug in this routine (if executable file name didn't match hardcoded value) that wasn't noticed until verification testing a different app.

Describe the solution you'd like
Add a functional test, should check for proper behavior or NOT_IMPLEMENTED.

Describe alternatives you've considered
None

Additional context
#111, functional test brought up in discussion for #207

Requester Info
Jacob Hageman - NASA/GSFC