Update API

• update some required parameters of the API.

Update the API for September

• 【Add】GET /api/v2/symbols/{symbol} endpoint
• 【Modify】POST /api/v1/hf/orders endpoint，add clientOid response param
• 【Modify】POST /api/v1/hf/orders/test endpoint，add clientOid response param
• 【Modify】POST /api/v1/hf/orders/sync endpoint，add clientOid response param
• 【Modify】POST /api/v1/hf/orders/alter endpoint，add clientOid response param
• 【Modify】POST /api/v1/hf/orders/multi endpoint，add clientOid response param
• 【Modify】POST /api/v1/hf/orders/multi/sync endpoint，add clientOid response param