[SPARK-22757][K8S] Enable spark.jars and spark.files in KUBERNETES mode

## What changes were proposed in this pull request?

We missed enabling `spark.files` and `spark.jars` in #19954. The result is that remote dependencies specified through `spark.files` or `spark.jars` are not included in the list of remote dependencies to be downloaded by the init-container. This PR fixes it.

## How was this patch tested?

Manual tests.

vanzin This replaces #20157.

foxish

Author: Yinan Li <liyinan926@gmail.com>

Closes #20160 from liyinan926/SPARK-22757.

(cherry picked from commit 6cff7d1)
Signed-off-by: Felix Cheung <felixcheung@apache.org>

Author: liyinan926

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -584,10 +584,11 @@ object SparkSubmit extends CommandLineUtils with Logging {
         confKey = "spark.executor.memory"),
       OptionAssigner(args.totalExecutorCores, STANDALONE | MESOS | KUBERNETES, ALL_DEPLOY_MODES,
         confKey = "spark.cores.max"),
-      OptionAssigner(args.files, LOCAL | STANDALONE | MESOS, ALL_DEPLOY_MODES,
+      OptionAssigner(args.files, LOCAL | STANDALONE | MESOS | KUBERNETES, ALL_DEPLOY_MODES,
         confKey = "spark.files"),
       OptionAssigner(args.jars, LOCAL, CLIENT, confKey = "spark.jars"),
-      OptionAssigner(args.jars, STANDALONE | MESOS, ALL_DEPLOY_MODES, confKey = "spark.jars"),
+      OptionAssigner(args.jars, STANDALONE | MESOS | KUBERNETES, ALL_DEPLOY_MODES,
+        confKey = "spark.jars"),
       OptionAssigner(args.driverMemory, STANDALONE | MESOS | YARN | KUBERNETES, CLUSTER,
         confKey = "spark.driver.memory"),
       OptionAssigner(args.driverCores, STANDALONE | MESOS | YARN | KUBERNETES, CLUSTER,