CONV() silently overflows returning wrong results

spark-sql> SELECT CONV(SUBSTRING('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', 3), 16, 10);

18446744073709551615

Time taken: 2.114 seconds, Fetched 1 row(s)

spark-sql> set spark.sql.ansi.enabled = true;

spark.sql.ansi.enabled true

Time taken: 0.068 seconds, Fetched 1 row(s)

spark-sql> SELECT CONV(SUBSTRING('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', 3), 16, 10);

18446744073709551615

Time taken: 0.05 seconds, Fetched 1 row(s)

In ANSI mode we should raise an error for sure.
In non ANSI either an error or a NULL maybe be acceptable.

Alternatively, of course, we could consider if we can support arbitrary domains since the result is a STRING again.