Fix production dependencies on 'google-protobuf' and 'hex2dec'

[ja30278]

Both 'google-protobuf' and 'hex2dec' are currently required by non-dev code, and should be included in the production dependency set.

google-protobuf:

• required by lib/imp/generated_proto/collector_pb.js

hex2dec:

• required by lib/imp/runtime_imp.js and lib/imp/span_imp.js