feat: signature rejection (#1472)

## Description

Adds support for rejecting a given document informing the document
owner.

Flows for resolving a rejection don't currently exist so it's up to the
document owner to reach out to the recipient and work out a way to move
forward via a new document or offline agreement.

## Related Issue


## Changes Made

- Added new rejection properties to the recipient schema
- Added API endpoints to support rejection
- Added email templates for notifying the document owner and recipient
- Added a dialog on the signing page to start the rejection flow.

## Testing Performed

- Manually tested the flow end to end
- Automated tests are planned

packages/lib/server-only/admin/get-recipients-stats.ts

@@ -13,6 +13,7 @@ export const getRecipientsStats = async () => {
     [ReadStatus.NOT_OPENED]: 0,
     [SigningStatus.SIGNED]: 0,
     [SigningStatus.NOT_SIGNED]: 0,
+    [SigningStatus.REJECTED]: 0,
     [SendStatus.SENT]: 0,
     [SendStatus.NOT_SENT]: 0,
   };