Add gradle-wrapper.jar into subproject to produce ready to use standalone .zip

Author: koperagen

examples/kotlin-dataframe-plugin-example/gradle/wrapper/gradle-wrapper.jar

@@ -0,0 +1,6 @@
+#Fri Jul 25 14:30:49 AMT 2025
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists