在 bluetopia的代码里只能看到 GATT_Initialize , GATT_Register_Service 用于初始化 Gatt Server 的函数，
用什么函数初始化 Gatt Client 并和Gatt server 建立联系？
我这里有两个 cc256x模块，cc256x_roleA, cc256x_roleB
服务接口:
UUID: D618D000-6000-1000-8000-000000000000
有2个子接口（Characteristics）：
1. Write Characteristic ( cc256x_roleA 向 BLE 设备 cc256x_roleB 发送信息或指令 。
UUID: D618D001-6000-1000-8000-000000000000
BLE Properties: Write
Date Type: Byte[] (固定长度字节数组，长度 20)
Date Length: 20
2. Notify Characteristic (提供给 BLE 设备 cc256x_roleB 向 cc256x_roleA 发送通知 信息或指令):
UUID: D618D002-6000-1000-8000-000000000000
BLE Properties: Notify
Date Type: Byte[] (固定长度字节数组，长度 20)
Date Length: 20