added ability to publish kotlin-client to maven local repo (#22438)

* this allows pushing client jar to local maven repository gradle -i clean jar publishToMavenLocal;  also generates jar with sources;

* this allows pushing client jar to local maven repository gradle -i clean jar publishToMavenLocal;  also generates jar with sources;

samples/client/petstore/kotlin-json-request-string/build.gradle

@@ -67,3 +67,18 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
         freeCompilerArgs += "-Xopt-in=kotlinx.serialization.ExperimentalSerializationApi"
     }
 }
+
+java {
+  withSourcesJar()
+}
+
+publishing {
+    publications {
+        maven(MavenPublication) {
+            groupId = 'org.openapitools'
+            artifactId = 'kotlin-petstore-json-request-string'
+            version = '1.0.0'
+            from components.java
+        }
+    }
+}