Improves the existing document rejection process by actually marking a
document as completed cancelling further actions.
## Related Issue
N/A
## Changes Made
- Added a new rejection status for documents
- Updated a million areas that check for document completion
- Updated email sending, so rejection is confirmed for the rejecting
recipient while other recipients are notified that the document is now
cancelled.
## Testing Performed
- Ran the testing suite to ensure there are no regressions.
- Performed manual testing of current core flows.
Implements a bulk send feature allowing users to upload a CSV file to
create multiple documents from a template. Includes CSV template
generation, background processing, and email notifications.
