[SPARK-29466][WEBUI] Show Duration for running drivers in Standalone master web UI

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to add a new column Duration for running drivers in Apache Spark Standalone master web UI in order to improve UX. This help users like the other Duration columns in the Running and Completed application tables.

Why are the changes needed?

When we use --supervise, the drivers can survive longer.
Technically, the Duration column is not the same. (Please see the image below.)

Does this PR introduce any user-facing change?

Yes. The red box is added newly.

How was this patch tested?

Manual since this is a UI column. After starting standalone cluster and jobs, kill the DriverWrapper and see the UI.

$ sbin/start-master.sh
$ sbin/start-slave.sh spark://$(hostname):7077
$ bin/spark-submit --master spark://(hostname):7077 --deploy-mode cluster --supervise --class org.apache.spark.examples.JavaSparkPi examples/target/scala-2.12/jars/spark-examples_2.12-3.0.0-SNAPSHOT.jar 1000
$ jps
41521 DriverWrapper
...
$ kill -9 41521   // kill the `DriverWrapper`.

[SparkQA]

Test build #112056 has finished for PR 26113 at commit fab5ec4.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

Retest this please

[SparkQA]

Test build #112176 has finished for PR 26113 at commit fab5ec4.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dbtsai]

LGTM. Thanks.

[dongjoon-hyun]

Thank you for review and approval, @dbtsai . Merged to master!