BLT is used by many multi-physics codes at LLNL, so to ease AMS adoption we should support BLT. - Move AMS build system from CMake to [BLT](https://llnl-blt.readthedocs.io/en/develop/index.html) - Ideally, keep supporting classic CMake and BLT
BLT is used by many multi-physics codes at LLNL, so to ease AMS adoption we should support BLT.