Add option to enable guessing the data type of each column

[magnusbaeck]

While it's now possible to manually indicate the data type of each column to avoid having a separate mutate filter for converting the type of the fields, the csv filter should be able to guess the type based on the field contents.

For backwards compatibility reasons this should be enabled via a new boolean option, e.g. auto_convert.

See https://discuss.elastic.co/t/logstash-csv-check-fields-for-numeric-and-mutate-to-integer/45293.

[daohodac]

+1

[ckiefer]

May I kindly ask for the status of this idea, I.e. To auto-guess column data types? Would it be asked too much to show the small piece of Ruby code that would achieve this too?

Kind regards Christoph