OS_ShellOutputToFile missing functional test

[skliper]

Is your feature request related to a problem? Please describe.
No functional test for OS_ShellOutputToFile

Describe the solution you'd like
Add functional test. Needed for build verification for any system that includes this capability.

Describe alternatives you've considered
At one point discussed removing this API, but CCB decided to make it optionally included

Additional context
#354

Requester Info
Jacob Hageman - NASA/GSFC

[skliper]

Note - low priority for now, current certification planned with this function excluded from the build