[SPARK-27159][SQL] update mssql server dialect to support binary type

## What changes were proposed in this pull request?

Change the binary type mapping from default blob to varbinary(max) for mssql server.
https://docs.microsoft.com/en-us/sql/t-sql/data-types/binary-and-varbinary-transact-sql?view=sql-server-2017
![image](https://user-images.githubusercontent.com/698621/54351715-0e8c8780-468b-11e9-8931-7ecb85c5ad6b.png)

## How was this patch tested?

Unit test.

Closes apache#24091 from lipzhu/SPARK-27159.

Authored-by: Zhu, Lipeng <lipzhu@ebay.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>

Author: zhulipeng

sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala

@@ -38,6 +38,7 @@ private object MsSqlServerDialect extends JdbcDialect {
     case TimestampType => Some(JdbcType("DATETIME", java.sql.Types.TIMESTAMP))
     case StringType => Some(JdbcType("NVARCHAR(MAX)", java.sql.Types.NVARCHAR))
     case BooleanType => Some(JdbcType("BIT", java.sql.Types.BIT))
+    case BinaryType => Some(JdbcType("VARBINARY(MAX)", java.sql.Types.VARBINARY))
     case _ => None
   }
 

sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala

@@ -860,6 +860,18 @@ class JDBCSuite extends QueryTest
       Some(TimestampType))
   }
 
+  test("MsSqlServerDialect jdbc type mapping") {
+    val msSqlServerDialect = JdbcDialects.get("jdbc:sqlserver")
+    assert(msSqlServerDialect.getJDBCType(TimestampType).map(_.databaseTypeDefinition).get ==
+      "DATETIME")
+    assert(msSqlServerDialect.getJDBCType(StringType).map(_.databaseTypeDefinition).get ==
+      "NVARCHAR(MAX)")
+    assert(msSqlServerDialect.getJDBCType(BooleanType).map(_.databaseTypeDefinition).get ==
+      "BIT")
+    assert(msSqlServerDialect.getJDBCType(BinaryType).map(_.databaseTypeDefinition).get ==
+      "VARBINARY(MAX)")
+  }
+
   test("table exists query by jdbc dialect") {
     val MySQL = JdbcDialects.get("jdbc:mysql://127.0.0.1/db")
     val Postgres = JdbcDialects.get("jdbc:postgresql://127.0.0.1/db")