Add a Format Feature activity

The Get Form Element Items from Features activity lets us specify a format string to be used in e.g. an itempicker, a checkgroup etc. The format string may contain fieldnames (in braces) that are replaced by the feature's attribute value.

I could use a new activity that does just that: Given a feature and a format string as input, return the formatted string. 

My workaround for now is to use a regular expression and For Each loop with a Text Replace, so having a dedicated activity would make my life much easier.