[SPARK-25043] print master and appId from spark-sql on startup

## What changes were proposed in this pull request?

A small change to print the master and appId from spark-sql as with logging turned down all the way (`log4j.logger.org.apache.spark.sql.hive.thriftserver.SparkSQLCLIDriver=WARN`), we may not know this information easily. This adds the following string before the `spark-sql>` prompt shows on the screen.

`Spark master: yarn, Application Id: application_123456789_12345`

## How was this patch tested?

I ran spark-sql locally and saw the appId displayed as expected.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Closes #22025 from abellina/SPARK-25043_print_master_and_app_id_from_sparksql.

Lead-authored-by: Alessandro Bellina <abellina@gmail.com>
Co-authored-by: Alessandro Bellina <abellina@yahoo-inc.com>
Signed-off-by: Thomas Graves <tgraves@apache.org>

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala

@@ -258,6 +258,8 @@ private[hive] object SparkSQLCLIDriver extends Logging {
     def continuedPromptWithDBSpaces: String = continuedPrompt + ReflectionUtils.invokeStatic(
       classOf[CliDriver], "spacesForString", classOf[String] -> currentDB)
 
+    cli.printMasterAndAppId
+
     var currentPrompt = promptWithCurrentDB
     var line = reader.readLine(currentPrompt + "> ")
 
@@ -323,6 +325,12 @@ private[hive] class SparkSQLCLIDriver extends CliDriver with Logging {
     hiveVariables.asScala.foreach(kv => SparkSQLEnv.sqlContext.conf.setConfString(kv._1, kv._2))
   }
 
+  def printMasterAndAppId(): Unit = {
+    val master = SparkSQLEnv.sparkContext.master
+    val appId = SparkSQLEnv.sparkContext.applicationId
+    console.printInfo(s"Spark master: $master, Application Id: $appId")
+  }
+
   override def processCmd(cmd: String): Int = {
     val cmd_trimmed: String = cmd.trim()
     val cmd_lower = cmd_trimmed.toLowerCase(Locale.ROOT)