Converted skypt to a callable app. Converted existing Makefile tests to...

Converted skypt to a callable app. Converted existing Makefile tests to gtests. Removed existing Makefile tests.  (#5444)

* Converted skypt to a callable app. Converted existing makefile tests to gtest format and removed old makefile tests and data. Addresses #5443.

* Updated contributor list to add Sarah S. Sutton. Addresses #5443.

---------

Co-authored-by: Sarah Sutton <ssutton@dhcp-10-142-214-177.uawifi.arizona.edu>