Support length, char_length, locate, regexp_extract

[PHILO-HE]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Currently, regexp_extract is lacking, which requires the execution at runtime fallback to vanilla spark and bring perf. overhead.

Describe the solution you'd like
Add regexp_extract expression support.

[zhouyuan]

Below 3 exprs might be related.

• length() : https://spark.apache.org/docs/latest/api/sql/#length
• char_length() : https://spark.apache.org/docs/latest/api/sql/#char_length
• locate: https://spark.apache.org/docs/latest/api/sql/#locate

[PHILO-HE]

Fixed.