GXP supfile integration and tests (#409)

* Updated stateAsJson to read both .sup and camera state jsons

* Added string sanitize function

* Moved statefile reader to utilities

* Added .sup filepath to linescan fixture

* Added test for model creation from sup file state

* Added sup file test data

* Added tests for sanitize and readFileInString

* Update hello.json

* Update UtilitiesTests.cpp

* Adds ability to modify GXP .sup Camera State using usgscsm_cam_test (#406)

* Adds ability to modify sup file with camera state or isd.

* Updated tests and documentation

* Added build artifact for usgscsm_cam_test executable

* Updated artifact target

* Added build artifact for usgscsm_cam_test executable (#408)

* Added build artifact for usgscsm_cam_test executable

* Updated artifact target

* Added test for supfile save and load

Co-authored-by: Amy Stamile <astamile@contractor.usgs.gov>
Co-authored-by: Amy Stamile <74275278+amystamile-usgs@users.noreply.github.com>