Add support to integration tests for Icarus Verilog. This is the main open source Verilog event based simulator that I'm aware of.

Motivation

We'd like to guarantee that we can produce Verilog that can (1) be consumed by existing tools and (2) simulates correctly with existing tools. We currently have integration tests that do this for Questa

Since #384 we can make use of the IR verification features of MLIR.

Our BConv op has a few parameter combinations where it can throw during Init or Prepare. In the converter we try to make sure that none of those cases will ev