feat: add multi subscription support (#734)

## Description

Previously we assumed that there can only be 1 subscription per user.
However, that will soon no longer the case with the introduction of the
Teams subscription.

This PR will apply the required migrations to support multiple
subscriptions.

## Changes Made

- Updated the Prisma schema to allow for multiple `Subscriptions` per
`User`
- Added a Stripe `customerId` field to the `User` model
- Updated relevant billing sections to support multiple subscriptions

## Testing Performed

- Tested running the Prisma migration on a demo database created on the
main branch

Will require a lot of additional testing.

## Checklist

- [ ] I have tested these changes locally and they work as expected.
- [ ] I have added/updated tests that prove the effectiveness of these
changes.
- [X] I have followed the project's coding style guidelines.

## Additional Notes

Added the following custom SQL statement to the migration:

> DELETE FROM "Subscription" WHERE "planId" IS NULL OR "priceId" IS
NULL;

Prior to deployment this will require changes to Stripe products:
- Adding `type` meta attribute

---------

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

apps/web/src/app/(dashboard)/admin/users/page.tsx

@@ -1,3 +1,5 @@
+import { getPricesByType } from '@documenso/ee/server-only/stripe/get-prices-by-type';
+
 import { UsersDataTable } from './data-table-users';
 import { search } from './fetch-users.actions';
 
@@ -14,12 +16,23 @@ export default async function AdminManageUsers({ searchParams = {} }: AdminManag
   const perPage = Number(searchParams.perPage) || 10;
   const searchString = searchParams.search || '';
 
-  const { users, totalPages } = await search(searchString, page, perPage);
+  const [{ users, totalPages }, individualPrices] = await Promise.all([
+    search(searchString, page, perPage),
+    getPricesByType('individual'),
+  ]);
+
+  const individualPriceIds = individualPrices.map((price) => price.id);
 
   return (
     <div>
       <h2 className="text-4xl font-semibold">Manage users</h2>
-      <UsersDataTable users={users} totalPages={totalPages} page={page} perPage={perPage} />
+      <UsersDataTable
+        users={users}
+        individualPriceIds={individualPriceIds}
+        totalPages={totalPages}
+        page={page}
+        perPage={perPage}
+      />
     </div>
   );
 }