[Enhancement] Support cast string to int

[wangsimo0]

Enhancement

StarRocks> select cast ('123.4' as INT) ;
+-----------------------+
I CAST ('1324.2' AS INT) |
+-----------------------+
|                   NULL |
+-----------------------+

in this SQL, 123.4 will be treated as a string and cannot be cast into int directly. In snowflake, hive, spark and MySQL, this is castable. However, in PostgreSQL, Clickhouse and trino, this is not castable.
Still a nice to have enhancement though.