Implement a benchmark for status update processing throughput.

In order to guide changes for improving status update throughput, a throughput benchmark can provide the data needed to justify structural changes to the code.

JMH seems to easily support benchmarks in which "synchronous" methods are called concurrently from multiple threads (which works for the current synchronous update code), but it is a bit trickier to leverage JMH for "asynchronous" code (if we were to process updates asynchronously, we become less interested in how long the statusUpdate(...) call takes, and more interested in the overall time it takes to process large numbers of updates).