Added ability to execute dict builder via Gradle

Leveraging Gradle to execute the builder makes the command
configuration much easier as the human engineer now does not
to set the Lucene classpath manually before running the command.

lucene/analysis/kuromoji/build.gradle

@@ -16,6 +16,7 @@
  */
 
 apply plugin: 'java-library'
+apply plugin: 'application'
 
 description = 'Japanese Morphological Analyzer'
 
@@ -25,3 +26,8 @@ dependencies {
 
   moduleTestImplementation project(':lucene:test-framework')
 }
+
+application {
+  mainModule = 'org.apache.lucene.analysis.kuromoji' // name defined in module-info.java
+  mainClass = 'org.apache.lucene.analysis.ja.dict.DictionaryBuilder'
+}