Provide serialization format option

[uupks]

Since zenoh can transport and store any format of data as long as it’s serializable as a bytes buffer,

can we provide other serialization format , such as protobuf with rosidl_typesupport_protobuf...

[clalancette]

It's certainly a possibility in the future. For now we are going to stick with CDR because it is easiest to implement, and makes bridging to DDS easier. But we'll keep this on the backlog to look at in the future.