[SPARK-48076][K8S] Promote KubernetesVolumeUtils to DeveloperApi

### What changes were proposed in this pull request?

This PR aims to promote `KubernetesVolumeUtils` to `DeveloperApi` from Apache Spark 4.0.0 for Apache Spark Kubernetes Operator.

### Why are the changes needed?

This API was added by the following at `Apache Spark 3.0.0` and has been stable.
- #22959

Since `Apache Spark Kubernetes Operator` requires this, we had better maintain it as a developer API officially from `Apache Spark 4.0.0`.
- apache/spark-kubernetes-operator#10

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #46326 from dongjoon-hyun/SPARK-48076.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/KubernetesVolumeUtils.scala

@@ -19,16 +19,25 @@ package org.apache.spark.deploy.k8s
 import java.lang.Long.parseLong
 
 import org.apache.spark.SparkConf
+import org.apache.spark.annotation.{DeveloperApi, Since, Unstable}
 import org.apache.spark.deploy.k8s.Config._
 
-private[spark] object KubernetesVolumeUtils {
+/**
+ * :: DeveloperApi ::
+ *
+ * A utility class used for K8s operations internally and Spark K8s operator.
+ */
+@Unstable
+@DeveloperApi
+object KubernetesVolumeUtils {
   /**
    * Extract Spark volume configuration properties with a given name prefix.
    *
    * @param sparkConf Spark configuration
    * @param prefix the given property name prefix
    * @return a Map storing with volume name as key and spec as value
    */
+  @Since("3.0.0")
   def parseVolumesWithPrefix(sparkConf: SparkConf, prefix: String): Seq[KubernetesVolumeSpec] = {
     val properties = sparkConf.getAllWithPrefix(prefix).toMap