Add better support for pointer return values in UT assert

[jphickey]

Is your feature request related to a problem? Please describe.
Currently, UT assert only as built-in support for 32-bit integer return values, in the form of UT_SetDefaultReturnValue and UT_SetDeferredRetcode. The majority of CFE/CFS APIs have a 32-bit integer return value, so this has been good enough.

However, there are also a fair number of CFE functions that return pointer values, and these int32 APIs do not currently work for pointer returns. Any stub that returns a pointer must have its own custom handler function to help set the return value, and so support is spotty. Every function that has a pointer return may have a slightly different way to control the return value, and a different range of things that can be done by the test to modify its behavior.

Describe the solution you'd like
Add two new APIs to UT assert:

• UT_SetDefaultReturnObject
• UT_SetDeferredReturnObject

These would work like the current integer functions, respectively, but accept pointers with a size instead of an integer. This type of signature could support ALL types of return values, including 8-bit, 16-bit, 64-bit, and potentially even larger structures (even though code should not output large structures via return value, it could be done).

Describe alternatives you've considered
A halfway point could be to just add generic reusable handlers that return a pointer, and could be registered to any function. But that would not be as clean, and would still need a separate function for each type.

Additional context
This can be added without breaking any currently-existing tests or stubs, because its only a new type of return record. It would not change anything about the existing logic, just extend it.

Requester Info
Joseph Hickey, Vantage Systems, Inc.