rpc客户端/服务端加入流式调用

[RFoe]

coasync/include/coasync/net/rpc/rpc_client.hpp

Lines 18 to 20 in 2e9135c

	template <typename R, typename... Args>
	COASYNC_ATTRIBUTE((nodiscard))
	awaitable<R> call(std::string const& __fn, Args&& ... __args)

或许是这样

net::serde_stream reply = client.call_streaming("get_bytes", 5);
for(unsigned int i {}; i < 5; i ++) {
    std::printf("%c\n", co_await reply.get<char>());
}