build-unit-test-docker: Add catch2 unit-test framework

This test framework is similar to googletest, but much more c++11
friendly and supports sectioned test semantics that are much more ugly
to implement in googletest.

https://github.com/catchorg/Catch2/blob/master/docs/why-catch.md

Change-Id: Icd547ba54e372e1656df58418c0dd1c661ca5a8d
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed