added another library to add and update helm repo

vars/addHelmRepo.groovy

@@ -0,0 +1,7 @@
+def call(String repoName, String repoUrl) {
+    container('helm') {
+        sh 'helm repo add ${repoName} ${repoUrl}'
+        sh 'helm repo update'
+        echo "Helm repository '${repoName}' added and updated"
+    }
+}