fix(proxy): apply proxy in mergeHttpOptions to ensure functionality

[While-Shark]

must set proxy at mergeHttpOptions() , otherwise the proxy not working

fix(proxy) base on #455 #455

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[While-Shark]

example with proxy

Client client = Client.builder()
.apiKey(API_KEY)
.httpOptions(HttpOptions.builder().timeout(30000)
.proxy(new Proxy(Proxy.Type.HTTP, new InetSocketAddress("127.0.0.1", 10808)))
.build())
.build()