Related PR: #32743

Problem Summary:
problem before this pr:
1. null type problem
the type of NULL is null_type, this will lead to error when select this view through jdbc catalog.
```sql
mysql> CREATE VIEW test_null COMMENT '测试null类型' AS SELECT NULL AS `col1`;
Query OK, 0 rows affected (0.02 sec)

mysql> desc test_null;
+-------+-----------+------+-------+---------+-------+
| Field | Type      | Null | Key   | Default | Extra |
+-------+-----------+------+-------+---------+-------+
| col1  | null_type | Yes  | false | NULL    |       |
+-------+-----------+------+-------+---------+-------+
1 row in set (0.00 sec)
```
after this pr, the type is changed to tinyint.
mysql> CREATE VIEW test_null2 COMMENT '测试null类型' AS SELECT NULL AS `col1`;
Query OK, 0 rows affected (0.03 sec)
```sql
mysql> desc test_null2;
+-------+---------+------+-------+---------+-------+
| Field | Type    | Null | Key   | Default | Extra |
+-------+---------+------+-------+---------+-------+
| col1  | tinyint | Yes  | false | NULL    |       |
+-------+---------+------+-------+---------+-------+
1 row in set (0.01 sec)
```
2. nullable problem
Modify the internal elements of nested types returned by JDBC to always be null, in order to maintain consistency with Doris' internal implementation
### Release note