Generate JMH json report with `ant microbench`

patch by Mick Semb Wever; reviewed by Tomek Łasica for CASSANDRA-16371

build.xml

@@ -1935,6 +1935,14 @@
                   <include name="**/*.jar" />
               </fileset>
           </classpath>
+          <arg value="-foe"/>
+          <arg value="true"/>
+          <arg value="-rf"/>
+          <arg value="json"/>
+          <arg value="-rff"/>
+          <arg value="${build.test.dir}/jmh-result.json"/>
+          <arg value="-v"/>
+          <arg value="EXTRA"/>
           <arg value=".*microbench.*${benchmark.name}"/>
       </java>
   </target>