config: Add --with-macos-firewall-rules option.
Activates automatic addition of firewall rules during testing on macOS to prevent firewall popup windows.
config.packages.MPI: Set mpiexecExecutable property (full path to mpiexec executable).
Activates automatic addition of firewall rules during testing on macOS to prevent firewall popup windows.
config.packages.MPI: Set mpiexecExecutable property (full path to mpiexec executable).