Use the built-in grpc-go client and server interceptor chaining
utilities, instead of the ones provided by go-grpc-middleware.
Simplify our interceptors to call their handlers/invokers directly,
instead of delegating to the metrics interceptor, and add the
metrics interceptor to the chains instead.
Add Honeycomb tracing to all Boulder components which act as
HTTP servers, gRPC servers, or gRPC clients. Add many values
which we currently emit to logs to the trace spans. Add a way to
configure the Honeycomb integration to our config files, and by
default configure all of our tests to "mute" (send nothing).
Followup changes will refine the configuration, attempt to reduce
the new dependency load, and introduce better sampling.
Part of https://github.com/letsencrypt/dev-misc-tickets/issues/218
Phil Porada