Change -emit-defaults behaviour so that the flag isn't anymore needed to show default values (Proto3)

Hi,
I encountered the same issue as described in #97.
After some debugging, I tried to call the ame service with BloomRPC GUI and default value was shown immediately.
Some research lead me to -emit-defaults option which solves the issue for me.
Although this is expected behaviour as explained in #97, it would be desirable to have -emit-defaults set by default and give the user the option to omit defaults if needed.
This is obviously how BloomRPC and other clients/client libraries work.

Or is there anything against this approach?

Thanks!

Start by locating the grpcurl command-line handling for the -emit-defaults flag and tracing how default values are emitted. Define the default behavior and the option for omitting defaults, then verify the CLI behavior against the Proto3 case described in the issue; no specific file or test is named.

Written by the indexing model from the issue text.