Major Description
In functions, CSV/JSON datasources and other places, when the pattern is default, use CAST logic in parsing strings to dates/timestamps.
Currently, TimestampFormatter.getFormatter() applies the default pattern yyyy-MM-dd HH:mm:ss when the pattern is not set, see https://github.com/apache/spark/blob/f2492772baf1d00d802e704f84c22a9c410929e9/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala#L344 . Instead of that, need to create a special formatter which invokes the cast logic.
