add runtime output and exit on fail

[cwentland0]

Adds runtime_step as a global variable in Exodus output. This records the wall clock runtime of each time step, for use in total runtime metrics.

Also, this terminates execution when a simulation has failed. Previously, if a simulation failed the time step outer loop would continue until the set final time, and repeatedly write the system state at failure to the output file. This made it difficult to determine after the fact whether a simulation had failed and wastes disk space. This ultimately does not address the edge case where the simulation fails on the final time step.

[ikalash]

Thanks for putting this in @cwentland0 ! It's very timely, as the termination feature will be helpful in some runs I'm doing now.