feat: add direct templates links (#1165)

## Description

Direct templates links is a feature that provides template owners the
ability to allow users to create documents based of their templates.

## General outline

This works by allowing the template owner to configure a "direct
recipient" in the template.

When a user opens the direct link to the template, it will create a flow
where they sign the fields configured by the template owner for the
direct recipient. After these fields are signed the following will
occur:

- A document will be created where the owner is the template owner
- The direct recipient fields will be signed
- The document will be sent to any other recipients configured in the
template
- If there are none the document will be immediately completed

## Notes

There's a custom prisma migration to migrate all documents to have
'DOCUMENT' as the source, then sets the column to required.

---------

Co-authored-by: Lucas Smith <me@lucasjamessmith.me>

packages/trpc/server/singleplayer-router/router.ts

@@ -13,6 +13,7 @@ import { getFile } from '@documenso/lib/universal/upload/get-file';
 import { putPdfFile } from '@documenso/lib/universal/upload/put-file';
 import { prisma } from '@documenso/prisma';
 import {
+  DocumentSource,
   DocumentStatus,
   FieldType,
   ReadStatus,
@@ -95,6 +96,7 @@ export const singleplayerRouter = router({
             // Create document.
             const document = await tx.document.create({
               data: {
+                source: DocumentSource.DOCUMENT,
                 title: documentName,
                 status: DocumentStatus.COMPLETED,
                 documentDataId,