This commit fixes FileReference attachments of multiple consequtive mails
that are sent via the mail queue, for example via the forms finisher with
a user and an admin mail, where files need to be attached to both mails.

[BUGFIX] Fix writing of the form configurations if the folder is ḿissing, Fix default form extension key to project_theme

[TASK] Add allmarker as default template content, fixed a bug where the template name could not be resolved