chore: fix serverExternalPackages errors in monorepo (#14535)

Fixes these:

<img width="1128" height="445" alt="image"
src="https://github.com/user-attachments/assets/fb2b3885-f913-49d3-b2e7-5ddf66619758"
/>

We have to add sentry to the externals list, and install `mongoose` at
the monorepo root, as it's external, and the resulting
`require(mongoose)` calls need to be resolvable from the top-level app
folder.

Author: AlessioGr

package.json

@@ -174,6 +174,7 @@
     "lint-staged": "15.2.7",
     "minimist": "1.2.8",
     "mongodb-memory-server": "10.1.4",
+    "mongoose": "8.15.1",
     "next": "15.4.4",
     "open": "^10.1.0",
     "p-limit": "^5.0.0",

packages/next/src/withPayload.js

@@ -88,6 +88,8 @@ export const withPayload = (nextConfig = {}, options = {}) => {
       '@payloadcms/drizzle',
       // External because they install @aws-sdk/client-s3:
       '@payloadcms/payload-cloud',
+      // External, because it installs import-in-the-middle and require-in-the-middle - both in the default serverExternalPackages list.
+      '@sentry/nextjs',
       // TODO: We need to externalize @payloadcms/storage-s3 as well, once Next.js has the ability to exclude @payloadcms/storage-s3/client from being externalized.
       // Do not bundle additional server-only packages during dev to improve compilation speed
       ...(process.env.NODE_ENV === 'development' && options.devBundleServerPackages === false