feat: force signature fields for document signers (#1139)

## Description

Show a dialog when the document has signers with no signature fields
placed.

## Changes Made

Created a new dialog that'll be triggered when the document owner tries
to send a document to the signers without placing signature fields. The
document owners can't proceed to the next step unless they add signature
fields.

## Checklist

- [x] I have tested these changes locally and they work as expected.
- [ ] I have added/updated tests that prove the effectiveness of these
changes.
- [ ] I have updated the documentation to reflect these changes, if
applicable.
- [x] I have followed the project's coding style guidelines.
- [ ] I have addressed the code review feedback from the previous
submission, if applicable.




https://github.com/documenso/documenso/assets/25515812/f1b5c34e-2ce0-40e3-804c-f05d23045710




<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Introduced "Direct Links" for async signing, allowing users to create
documents from templates using public links.
- Added `MissingSignatureFieldDialog` component to ensure users don't
miss adding signature fields.

- **Enhancements**
- Updated blog content to provide guidance on contract management and
announce new pricing plans.

- **Bug Fixes**
  - Improved async signing process for better efficiency and control.

- **Refactor**
- Improved internal code structure and import order for stripe-related
functionality.

- **Tests**
- Enhanced e2e tests to verify signature presence before document
creation and updated test flows for document approval.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: David Nguyen <davidngu28@gmail.com>

packages/ui/primitives/document-flow/missing-signature-field-dialog.tsx

@@ -0,0 +1,46 @@
+'use client';
+
+import { DialogClose } from '@radix-ui/react-dialog';
+
+import { Button } from '@documenso/ui/primitives/button';
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from '@documenso/ui/primitives/dialog';
+
+export type MissingSignatureFieldDialogProps = {
+  isOpen: boolean;
+  onOpenChange: (value: boolean) => void;
+};
+
+export const MissingSignatureFieldDialog = ({
+  isOpen,
+  onOpenChange,
+}: MissingSignatureFieldDialogProps) => {
+  return (
+    <Dialog open={isOpen} onOpenChange={onOpenChange}>
+      <DialogContent className="max-w-lg" position="center">
+        <DialogHeader>
+          <DialogTitle>No signature field found</DialogTitle>
+          <DialogDescription>
+            <p className="mt-2">
+              Some signers have not been assigned a signature field. Please assign at least 1
+              signature field to each signer before proceeding.
+            </p>
+          </DialogDescription>
+        </DialogHeader>
+        <DialogFooter>
+          <DialogClose asChild>
+            <Button type="button" variant="secondary">
+              Close
+            </Button>
+          </DialogClose>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+};