v3d/simulator: general improvements

We have been working with a newer version of the simulator, and when some tests started to fail, we realized that there were several things that we could do better.

So although several of the commits here are needed to avoid regressions when using such newer version, they are also to be done with the current one, so I'm sending this before the MR to enable the newer version.

The general rule is that we should try to do things more similar to how we do things at the kernel. It is worth to note that although this MR does some of that stuff with some commits, there are still room for getting both more similar.