Add formats parameter to parse_timestamp

[mattnthat]

As per conversation on this thread

With the removal of the to_timestamp function, it's become harder to handle / normalise unknown timestamps in input data.

The feature as suggested by @jszwedko is to extend parse_timestamp to accept a 'format' parameter which can be an array of timestamp formats to try to match.
This puts control of the timestamp format array onto the user (vector.dev team don't have to hardcode and constantly extend acceptable formats) but gives the user a simple way to match a wide variery of timestamp formats in the incoming data.

Work around suggested in the comment thread above gives some good structure around how the feature could work:

formats = ["%+c", "some other format"]
t1 = now() # default
for_each(formats) -> |_index, format| {
  t2, err = parse_timestamp(.timestamp, "some other format")
  if err == null {
    t1 = t2
  }
}
.timestamp = t1

[jszwedko]

Thanks @mattnthat ! Note the function already takes a format parameter to specify the format, as seen in the example you shared, but the change I think would be useful to have here is an optional formats parameter that accepts an array of valid formats.

[mattnthat]

Thanks @mattnthat ! Note the function already takes a format parameter to specify the format, as seen in the example you shared, but the change I think would be useful to have here is an optional formats parameter that accepts an array of valid formats.

Noted! Updated Issue title to reflect formats