test: Add benchmarks.

The benchmarks can be run using 'mvn verify -Pbenchmark'.

Change-Id: I13058f52bea77aa3cb4f1967126c28e1e98d1838
diff --git a/pom.xml b/pom.xml
index fe93b23..b346411 100644
--- a/pom.xml
+++ b/pom.xml
@@ -61,6 +61,7 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 
     <compiler-plugin.version>3.13.0</compiler-plugin.version>
+    <exec-maven-plugin.version>3.2.0</exec-maven-plugin.version>
     <failsafe-plugin.version>${surefire-plugin.version}</failsafe-plugin.version>
     <flatten-plugin.version>1.6.0</flatten-plugin.version>
     <google-java-format.version>1.15.0</google-java-format.version>
@@ -197,6 +198,12 @@
         </configuration>
       </plugin>
 
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>${exec-maven-plugin.version}</version>
+      </plugin>
+
     </plugins>
   </build>