检查命令正确性

dryrun选项用于检查所传入命令的正确性。在命令中添加“--dryrun”选项，执行校验后打印请求报文，跳过实际运行，不调用目标API：

hcloud RDS CreateConfiguration --cli-region="cn-north-4" --project_id="0dd8cb****************19b5a84546" --datastore.type="MySQL" --datastore.version="5.7" --values.max_connections="10" --name="test-001" --description="test create configuration" --dryrun
--------------------------------- dry-run模式跳过实际运行,当前请求为: ---------------------------------
POST https://rds.cn-north-4.myhuaweicloud.com/v3/0dd8cb****************19b5a84546/configurations
Content-Type: application/json
X-Project-Id: 0dd8cb****************19b5a84546
X-Sdk-Date: 20220621T103331Z
Authorization: ****

{
  "datastore": {
    "type": "MySQL",
    "version": "5.7"
  },
  "description": "test create configuration",
  "name": "test-001",
  "values": {
    "max_connections": "10"
  }
}