fix: add missing email reply validation (#1934)

## Description

General fixes to the email domain features

Changes made:
- Add "email" validation for "Reply-To email" fields
- Fix issue where you can't remove the "Reply-To" email after it's set
- Fix issue where setting the "Sender email" back to Documenso would
still send using the org/team pref

apps/remix/app/components/general/document/document-edit-form.tsx

@@ -289,7 +289,7 @@ export const DocumentEditForm = ({
           message,
           distributionMethod,
           emailId,
-          emailReplyTo,
+          emailReplyTo: emailReplyTo || null,
           emailSettings: emailSettings,
         },
       });