Add "String to JSON" action

Dear Nintex-Team,

please create a new action to support string to JSON conversion.

When we use the "Call a web service"-action, we often need to use JSON to assign it to "Request content".

currently, we help ourself with regex, modify string and looping over a collection to convert a string to JSON.

Assume you have a string with characters like " and ' and also CRLF, TAB and so on.

A lot of work and error prone...

Please support us with such an action. - Thanks!