Add cmake based testing

[mborland]

@jzmaddock, @ckormanyos, and @NAThompson this repo is a mirror of boostorg/math that allows development on CUDA architectures. B2 does not support CUDA so first order of business is getting some Cmake testing running so we can run the CUDA tests in CI. Investigation on how to get CI to work can be found: cppalliance/decimal#712