No null pointer check on TblHandles in CFE_TBL_GetAddresses and CFE_TBL_ReleaseAddresses

[nmullane]

Describe the bug
CFE_TBL_GetAddresses does not check that the array of TblHandles is not NULL and will cause a segmentation fault. A similar issue appears to also exist in CFE_TBL_ReleaseAddresses.

To Reproduce
Steps to reproduce the behavior:

1. The following line from my fork for Add table api functional tests #1734 will cause a segmentation fault instead of gracefully returning a CFE_TBL_BAD_ARGUMENT
   UtAssert_INT32_EQ(CFE_TBL_GetAddresses((void ***)&TblPtrs, numValidTbls, NULL), CFE_TBL_BAD_ARGUMENT);
   Whereas when the input TblPtrs is NULL, CFE_TBL_BAD_ARGUMENT is correctly returned.
2. Similarly the following line will cause a segmentation fault from CFE_TBL_ReleaseAddresses
   UtAssert_INT32_EQ(CFE_TBL_ReleaseAddresses(numValidTbls, NULL), CFE_TBL_BAD_ARGUMENT);

Expected behavior

• CFE_TBL_GetAddresses should return CFE_TBL_BAD_ARGUMENT when the pointer TblHandles is NULL.
• CFE_TBL_ReleaseAddresses should return CFE_TBL_BAD_ARGUMENT when the pointer TblHandles is NULL.

System observed on:

• Hardware: PC
• OS: Ubuntu 20.04

Reporter Info
Niall Mullane - GSFC 582 Intern