chore(core/protocols): http binding and cbor serializer refactoring

[kuhe]

This refactors two areas:

• some HTTP binding serde code has been moved from HttpProtocol to HttpBindingProtocol. Because RpcProtocol extends HttpProtocol, HttpProtocol should not handle any HTTP binding traits. RPC models generally don't have any http binding traits, but the correct course of action is to ignore them rather than expecting the model to remove them.

For example, hypothetically, the model could declare support for one RPC protocol and one REST protocol. In this case, the http binding traits must remain in the model.

• Some serialization transform code for CBOR has been moved from a separate internal function to the actual CborShapeSerializer class. The external function was initially planned for reuse, but this is no longer the case.