### What changes were proposed in this pull request?
Since SPARK-22757, `KubernetesUtils` has been used as an important utility class by all K8s modules and `ExternalClusterManager`s. This PR aims to promote `KubernetesUtils` to `DeveloperApi` in order to maintain it officially in a backward compatible way at Apache Spark 3.2.0.
### Why are the changes needed?
Apache Spark 3.1.1 makes `Kubernetes` module GA and provides an extensible external cluster manager framework. To have `ExternalClusterManager` for K8s environment, `KubernetesUtils` class is crucial and needs to be stable. By promoting to a subset of K8s developer API, we can maintain these more sustainable way and give a better and stable functionality to K8s users.
In this PR, `Since` annotations denote the last function signature changes because these are going to become public at Apache Spark 3.2.0.
| Version | Function Name |
|-|-|
| 2.3.0 | parsePrefixedKeyValuePairs |
| 2.3.0 | requireNandDefined |
| 2.3.0 | parsePrefixedKeyValuePairs |
| 2.4.0 | parseMasterUrl |
| 3.0.0 | requireBothOrNeitherDefined |
| 3.0.0 | requireSecondIfFirstIsDefined |
| 3.0.0 | selectSparkContainer |
| 3.0.0 | formatPairsBundle |
| 3.0.0 | formatPodState |
| 3.0.0 | containersDescription |
| 3.0.0 | containerStatusDescription |
| 3.0.0 | formatTime |
| 3.0.0 | uniqueID |
| 3.0.0 | buildResourcesQuantities |
| 3.0.0 | uploadAndTransformFileUris |
| 3.0.0 | uploadFileUri |
| 3.0.0 | requireBothOrNeitherDefined |
| 3.0.0 | buildPodWithServiceAccount |
| 3.0.0 | isLocalAndResolvable |
| 3.1.1 | renameMainAppResource |
| 3.1.1 | addOwnerReference |
| 3.2.0 | loadPodFromTemplate |
### Does this PR introduce _any_ user-facing change?
Yes, but this is new API additions.
### How was this patch tested?
Pass the CIs.
Closes#32406 from dongjoon-hyun/SPARK-35280.
Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
4e8701a77d