Add silent mode to perfect foresight simulations

See https://forum.dynare.org/t/supressing-output-in-steady-and-simul-commands/13916

added enhancement label

Note that it is already possible to do options_.verbosity = 0;, but we should add a documented interface to that feature.

@sebastien I agree, but we need to transform the various disp and fprintf-commands in perfect_foresight_solver to disp_verbose-commands to make that option functional.

assigned to @houtanb

closed via commit 7712a02f