[FEA] better regexp_extract support

[nvliyuan]

I wish we can support terms ending with line anchors in regexp_extract function:

from pyspark.sql.functions import regexp_extract
from pyspark.sql.types import StructType, StructField, StringType
schema = StructType([
    StructField('id', StringType(), True),
    StructField('text', StringType(), True)
])
data = [('1', 'aaa12'),
        ('2', 'bbb123'),
        ('3', 'ccc')]
df = spark.createDataFrame(data=data, schema=schema)
result = df.withColumn("numbers", regexp_extract("text", "(12$|123$)", 1))
result.show()

[NVnavkumar]

This is a duplicate of a #6882