[ISSUE apache#690] Support batch msgs in dledger mode (apache#2406)

* implement issue-690

* add unit test

* fix version

* fix wroteOffset;update version;polish

* polish

* fix wrong wroteOffset of AppendMessageResult

* move serialization out of lock in async method

Author: TerrellChen

store/pom.xml

@@ -31,7 +31,7 @@
         <dependency>
             <groupId>io.openmessaging.storage</groupId>
             <artifactId>dledger</artifactId>
-            <version>0.2.0</version>
+            <version>0.2.2</version>
             <exclusions>
                 <exclusion>
                     <groupId>org.apache.rocketmq</groupId>