Implement real async COS image upload

pom.xml

@@ -66,6 +66,11 @@
       <artifactId>lombok</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>com.qcloud</groupId>
+      <artifactId>cos_api</artifactId>
+      <version>5.6.247</version>
+    </dependency>
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>