2.5D Occlusion and Testing Update (#3757)

* Adds occlusion handling to cam2map

* Added conditional check for occlusion, updated xml

* Updated documentation

* Converted cam2map to a function style application

* Converted map2cam to cpp / functions

* Added new cam2map file and test file

* Moved cam2map gui helpers into the main.cpp

* Added baseline cam2map gtest

* Added a projected version of the default cube with a mapping for mars

* Updated map2cam for testability

* Added a gtest for map2cam

* Mocked rubbersheet and added initial cam2map test with mocked process

* Added initial mock file.

* Added cam2map transform tests, new line scanner fixture, and a mocked camera

* Fixed a few things in the cam2map tests

* Updated ISD and fixed paths

* Added more tests

* Updated fromisd with necessary camera load for some data sources

* Added cam2map mock tests, added bodies for transform pure virtual funcs

* Updated gtest to latest version

* Fixed a few things after the rebase

* Removed a cout

Co-authored-by: Austin Sanders <arsanders@usgs.gov>