Reduce compiler warnings for CUDA

[BradWhitlock]

This PR takes a stab at reducing the number of compiler warnings issued on CUDA machines. There are still various warnings about using host functions in host device code that have not yet been addressed.

• Various fixes for compiler warnings
• Suppress warning for host constexpr functions in host device code in one of the matrix host-configs
• Work around a test failure where Conduit was unable to read a YAML baseline (we convert to JSON on the fly and use that). It seems like a Conduit problem with that particular build.

[kennyweiss]

Thanks @BradWhitlock !