consolidate unit tests

[headupinclouds]

Maintaining per module CTests adds both compilation time (especially w/ exe level LTO processing) and execution time (primarily adb upload + setup). The non LTO android toolchain is still timing out, for example, due to the additional time required for NDK and SDK/emulator setup. Consolidating unit tests into a single GTest executable that is provided a full set of assets/models and test images should reduce CI build+test times significantly. Some changes to gauze may be required to make this clean, and it relates in part to hunter-packages/gauze#1. Currently gauze uses a generator expression syntax on the command line for resources to be uploaded for remote testing. In the case of a large test it is probably cleaner to provide a single json file (or similar) containing the key=value model file entires (as provided in the drishti-asssets package) and another json file containing the full set of test images and associated ground truth models in key=value form.

[headupinclouds]

PR: #583

[headupinclouds]

#588