For each function called by a fuzz worker, record whether the call succeeded or reverted. If it reverted, keep track of the revert reason for metrics.

At the end of a fuzz run, count up the total number of calls/reverts/revert reasons for each function and display them to the user in some way.

Stretch goal: allow the fuzzer to compare the previous run's reversion metrics to the results of the current run. This would allow detecting big issues in the harness or give dopamine hits for improving the harness.