Adding helper method in AbstractUnitTest for returning a mock FormEvent instance
Adding logic to the mime type form subscriber, responsible for setting the mime type on the IssueAttachment instance after submitting to the form
Integrating the mime type form subscriber with the IssueAttachmentFormType, updating test logic
Fixing scope of project PickerController in the container config (should be "request" scope)
Adding form.alias tag to IssueAttachmentFormType in the container
Update logic for IssueAttachmentMimeTypeFormSubscriber so that it handles empty form data correctly
Integrating attachments into the IssueFormType