Support database related DDLs (don't need return values) through sqlUpdate() method in TableEnvironment

According to FLIP-69, we should support such following DDLs related to the database in the TableEnvironment through `sqlUpdate()` method.

1. createDatabaseStatement:
CREATE DATABASE [ IF NOT EXISTS ] [ catalogName.] dataBaseName
[ COMMENT database_comment ]
[WITH ( name=value [, name=value]*)]

2. dropDatabaseStatement:
DROP DATABASE [ IF EXISTS ] [ catalogName.] dataBaseName
[ (RESTRICT|CASCADE)]

3. alterDatabaseStatement:
ALTER DATABASE [ catalogName.] dataBaseName SET
( name=value [, name=value]*)

4. useDatabaseStatement:
USE [ catalogName.] dataBaseName