[SPARK-10845] [SQL] Makes spark.sql.hive.version a SQLConfEntry

When refactoring SQL options from plain strings to the strongly typed `SQLConfEntry`, `spark.sql.hive.version` wasn't migrated, and doesn't show up in the result of `SET -v`, as `SET -v` only shows public `SQLConfEntry` instances. This affects compatibility with Simba ODBC driver.

This PR migrates this SQL option as a `SQLConfEntry` to fix this issue.

Author: Cheng Lian <lian@databricks.com>

Closes #8925 from liancheng/spark-10845/hive-version-conf.

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/HiveThriftServer2.scala

@@ -55,7 +55,6 @@ object HiveThriftServer2 extends Logging {
   @DeveloperApi
   def startWithContext(sqlContext: HiveContext): Unit = {
     val server = new HiveThriftServer2(sqlContext)
-    sqlContext.setConf("spark.sql.hive.version", HiveContext.hiveExecutionVersion)
     server.init(sqlContext.hiveconf)
     server.start()
     listener = new HiveThriftServer2Listener(server, sqlContext.conf)

sql/hive-thriftserver/src/test/scala/org/apache/spark/sql/hive/thriftserver/HiveThriftServer2Suites.scala

@@ -21,6 +21,7 @@ import java.io.File
 import java.net.URL
 import java.sql.{Date, DriverManager, SQLException, Statement}
 
+import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.duration._
@@ -431,6 +432,32 @@ class HiveThriftBinaryServerSuite extends HiveThriftJdbcTest {
       }
     )
   }
+
+  test("Checks Hive version via SET -v") {
+    withJdbcStatement { statement =>
+      val resultSet = statement.executeQuery("SET -v")
+
+      val conf = mutable.Map.empty[String, String]
+      while (resultSet.next()) {
+        conf += resultSet.getString(1) -> resultSet.getString(2)
+      }
+
+      assert(conf.get("spark.sql.hive.version") === Some("1.2.1"))
+    }
+  }
+
+  test("Checks Hive version via SET") {
+    withJdbcStatement { statement =>
+      val resultSet = statement.executeQuery("SET")
+
+      val conf = mutable.Map.empty[String, String]
+      while (resultSet.next()) {
+        conf += resultSet.getString(1) -> resultSet.getString(2)
+      }
+
+      assert(conf.get("spark.sql.hive.version") === Some("1.2.1"))
+    }
+  }
 }
 
 class HiveThriftHttpServerSuite extends HiveThriftJdbcTest {

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala

@@ -610,6 +610,11 @@ private[hive] object HiveContext {
     doc = "Version of the Hive metastore. Available options are " +
         s"<code>0.12.0</code> through <code>$hiveExecutionVersion</code>.")
 
+  val HIVE_EXECUTION_VERSION = stringConf(
+    key = "spark.sql.hive.version",
+    defaultValue = Some(hiveExecutionVersion),
+    doc = "Version of Hive used internally by Spark SQL.")
+
   val HIVE_METASTORE_JARS = stringConf("spark.sql.hive.metastore.jars",
     defaultValue = Some("builtin"),
     doc = s"""