Display configuration parameters in Verilator simulation

[imphil]

To help users identify how their Verilator simulation of Ibex was built it would be nice to display the parameters (or name of the configuration) that were chosen when running the simulation -- either by default, or as part of a config parameter (e.g. --version).

The parameter values should be available from Verilator at runtime, so we probably don't need any compile-time magic to pass them in.