This PR is handles the changes required to support envelopes. The new
envelope editor/signing page will be hidden during release.
The core changes here is to migrate the documents and templates model to
a centralized envelopes model.
Even though Documents and Templates are removed, from the user
perspective they will still exist as we remap envelopes to documents and
templates.
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.
