Consider reporting Grpc.Net.Client versions

[jskeet]

We add assembly versions in ServiceSettingsBase - let's include more assemblies.

[jskeet]

(Instead of adding Grpc.Net.Client, we may end up just changing where we take the version number from, given the way these are reported. I'm not sure how easy it is to differentiate between Grpc.Net.Client and Grpc.Core at this point.)

[amanda-tarafa]

The part where we report protobuf version has been completed in #833 and it's tracked by b/415813788. I'm changing the description of this issue accordingly.