Add command line option to read the configuration dumped by the MLIR crash
reproducer and adds those to the other command line options parsed by mlir-opt.
Simple convenience that enables mlir-opt --run-reproducer /tmp/repro.mlir
instead of needing to copy&paste the configuration. It is very simple and
doesn't try to do anything advanced (e.g., configuration has to be in first
line, it only parses the configuration). Based parsing on EnvVar parsing in