Fix #55, Moves interface definition files to inc

[chillfig]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution

• Fixes Move interface definition files to "inc" location #55

Testing performed
make install
lcov

Expected behavior changes
No expected behavior change.

System(s) tested on
-Ubuntu 18.04

Additional context
N/A

Third party code
If included, identify any third party code and provide text file of license

Contributor Info - All information REQUIRED for consideration of pull request
-Justin Figueroa, Vantage

[chillfig]

@jphickey Any ideas why this implementation fails to build? (CI workflow error message: https://github.com/nasa/CS/actions/runs/3576815445/jobs/6015077775#step:9:91)

[jphickey]

@jphickey Any ideas why this implementation fails to build? (CI workflow error message: https://github.com/nasa/CS/actions/runs/3576815445/jobs/6015077775#step:9:91)

Yes, this line is not correct: https://github.com/chillfig/CS/blob/dab326390e82838f357024b01cf20357f610a6f4/CMakeLists.txt#L3

Target name should be first. So something line target_include_directories(cs PUBLIC fsw/inc)....

Grep for "target_include_directories" if you need more examples ... plenty of examples of usage of this command in CFE and OSAL.