[SQL][MINOR] Fix minor formatting issues in SHOW CREATE TABLE output

## What changes were proposed in this pull request?

This PR fixes two minor formatting issues appearing in `SHOW CREATE TABLE` output.

Before:

```
CREATE EXTERNAL TABLE ...
...
WITH SERDEPROPERTIES ('serialization.format' = '1'
)
...
TBLPROPERTIES ('avro.schema.url' = '/tmp/avro/test.avsc',
  'transient_lastDdlTime' = '1466638180')
```

After:

```
CREATE EXTERNAL TABLE ...
...
WITH SERDEPROPERTIES (
  'serialization.format' = '1'
)
...
TBLPROPERTIES (
  'avro.schema.url' = '/tmp/avro/test.avsc',
  'transient_lastDdlTime' = '1466638180'
)
```

## How was this patch tested?

Manually tested.

Author: Cheng Lian <lian@databricks.com>

Closes apache#13864 from liancheng/show-create-table-format-fix.

Author: liancheng

sql/core/src/main/scala/org/apache/spark/sql/execution/command/tables.scala

@@ -830,7 +830,7 @@ case class ShowCreateTableCommand(table: TableIdentifier) extends RunnableComman
           s"'${escapeSingleQuotedString(key)}' = '${escapeSingleQuotedString(value)}'"
       }
 
-      builder ++= serdeProps.mkString("WITH SERDEPROPERTIES (", ",\n  ", "\n)\n")
+      builder ++= serdeProps.mkString("WITH SERDEPROPERTIES (\n  ", ",\n  ", "\n)\n")
     }
 
     if (storage.inputFormat.isDefined || storage.outputFormat.isDefined) {
@@ -864,7 +864,7 @@ case class ShowCreateTableCommand(table: TableIdentifier) extends RunnableComman
       }
 
       if (props.nonEmpty) {
-        builder ++= props.mkString("TBLPROPERTIES (", ",\n  ", ")\n")
+        builder ++= props.mkString("TBLPROPERTIES (\n  ", ",\n  ", "\n)\n")
       }
     }
   }