Converts a String to a date. For example, given a schema such as:

{
  "type": "record",
  "name": "events",
  "fields": [
    { "name": "name", "type": "string" },
    { "name": "eventDate", "type" : "string"}
  ]
}

and a record such as:

{
  "name" : "My Event",
  "eventDate" : "2017-10-20'T'11:00:00'Z'"
}

The following record path would parse the eventDate field into a Date:

toDate( /eventDate, "yyyy-MM-dd'T'HH:mm:ss'Z'")