Support lower case fieldNames in partitioning for s3

[mam8270]

Issue Guidelines

Amazon s3 partition structure requires lowercase names when used with athena, but there is a not an easy way to achieve this.
https://docs.aws.amazon.com/athena/latest/ug/partitions.html#partitions-considerations-limitations

Based on the documentation I would expect something like this to work:
SELECT userId AS 'userid' PARTITIONBY 'userid'

This doesn't seem to work and publishes the uppercase field name. There actually doesn't seem to be any good way when using partionby and a json document to partition on the lower case version of the field.