Initial findfeatures app conversion + gtests (#4163)

* Initial findfeatures conversion + gtests

* Delete makefiles

* Addressed PR feedback

Removed unnecessary cube.h from findfeatures.h
Removed additional cube reopens from threeimagenetwork fixture.
Added a comment clarifying empty lat/lon values in match test.

* Removed template comment

* Removed unused AddFeatures function

* Edited test for lat/lon in geomsource

* Edited maxpoints test to compare multiple runs of findfeatures