Fix createUserFromEmail where email would not contain username and fullname

Patch to fix issue #545 where a user created from email will fail to receive credentials in the confirmation mail. Handlebars seems to have an issue with accessing properties not being owned by its parent :

Handlebars: Access has been denied to resolve the property "fullname" because it is not an "own property" of its parent.
You can add a runtime option to disable the check or this warning:
See https://handlebarsjs.com/api-reference/runtime-options.html#options-to-control-prototype-access for details
Handlebars: Access has been denied to resolve the property "username" because it is not an "own property" of its parent.
You can add a runtime option to disable the check or this warning:
See https://handlebarsjs.com/api-reference/runtime-options.html#options-to-control-prototype-access for details

I couldn't figure a way to keep the template using user.username so I made a copy of these properties in dataObject and replaced these variables in the mail template.

I kept the original user: savedUser in dataObject just in case the callback was using it later to avoid breaking anything :

https://github.com/polonel/trudesk/blob/5bbc42395de7d2589daa97d6837500826448ac11/src/models/user.js#L599

polonel / trudesk

Fix createUserFromEmail where email would not contain username and fullname #553