Doris do not support explicitly cast NULL_TYPE to ANY type .
```
mysql> select cast(NULL as int);
ERROR 1105 (HY000): errCode = 2, detailMessage = Invalid type cast of NULL from NULL_TYPE to INT
```
So we should also forbid user from casting NULL_TYPE to ARRAY type.
This commit will produce the following effect:
```
mysql> select cast(NULL as array<int>);
ERROR 1105 (HY000): errCode = 2, detailMessage = Invalid type cast of NULL from NULL_TYPE to ARRAY<INT(11)>
```
e84d9a6c87