Logging: ability to modify `StartCall` and `FinishCall` default messages

[elmarsan]

Hey,

I've been digging into the code of the logging interceptor, looking for a way to change the default messages associated with the StartCall and FinishCall events. Currently, the interceptor always logs started call and finished call, and I don't think there is a way to customize these messages, for example, to include the gRPC service name or any other desired information.

Are you planning to make these messages configurable?

[johanbrandhorst]

Hi, thanks for your issue! Probably not, tbh. I think for this type of thing, just go ahead and fork us, the interceptors rarely change. If you can find that this is something a lot of users want, we could consider merging it back, but I'm not convinced.