Implement c++ native lib for streaming proto, part 1

Extract protobuf class out and creates EncodedBuffer class
which holds protobuf data.
Next step is to create a ProtoOutputStream and let incident helper
adapt the change as well.
please see frameworks/base/core/java/android/util/proto

Bug: 65641021
Test: unit tested
Change-Id: I0dd343b2e62d60f091c8f857fae3452ec8da6b96