As a User, I can create templates in txt format.

Using txt template, users can define a special content format like html, xml, csv or plain text.

The main goal is allow customer rename the generated file to the file type desired.

Note from duplicated issue:
Creating .txt templates to export data would be great. With this feature, users will be able to export data to xml files, for example. The output format will be .txt but the content can be xml. So, to get an xml file the user only need to change the extension file