Add extra events needed in hh-tracer

[fvictorio]

Besides the beforeMessage, step, and afterMessage events, hardhat-tracer uses the beforeTx, afterTx and newContract events, so we should add them. I think the first two are going to be easy and only need changes in the Hardhat side; the newContract one seems harder.

Definition of done

The following events can be used. As with the events we have now, we don't need to pass the same data as ethereumjs; a partial object with just the fields needed by hh-tracer is enough:

• vm.events.on("beforeTx", ...)
• vm.events.on("afterTx", ...)
• vm.evm.events.on("newContract", ...)