- rework simdrv_defs into a package
- use SV queues instead of dynamic arrays in the APIs (as they resemble C++'s std::vector a bit more, hence are more convenient to use)
- added AXI4 BFMs from the PULP project library
- added a bunch of simulation drivers (for the VUART & LM32 MCS cores)
- added a trivial unit test/logging "framework" (see logger.svh)

Note these changes will break your legacy testbenches, here's how to fix the most common issues:
- Replace the includes of simdrv_defs.svh indo an include of "gencores_sim_defs.svh" followed by
  import of gencores_sim_pkg package
- If your code uses CBusAccessor::readm/writem, change the addr/data parameters to use SV queues instead of dynamic arrays