Add permissions per form-processor
form-processor instances can be bound to existing permissions already, but that may be insufficient or misleading, when a form processor is bound to semantically "foreign" permissions, that will also allow for other actions (i.e. "View Contributions" allows viewing all contributions, whereas a form processor instance might want to limit things.
There should be an option to select that a form processor instance provide its own permission, instead of using an existing one.