fix: use thumbnailUrl for upload documents in folder view (#13368)

### What?
Fix the folder view for upload documents only using
`formatFolderOrDocumentItem()` function and only if the upload is an
image, even when there's a `thumbnailURL` available.

### Why?
Folder view for upload collections (especially those with sharp resizing
disabled) renders different thumbnails between the folder view and list
view. With sharp resizing disabled and an `adminThumbnail` fn provided,
the list view will correctly render optimised images, while the folder
view renders full source images - resulting in a huge discrepancy in
loaded image sizes.

### How?
We're passing the `value.thumbnailURL` **before** the
`formatFolderOrDocumentItem()` call rather than passing it directly as a
function parameter to cover cases where non-image uploads have a
`thumbnailURL` defined.

Fixes #13246

Author: damnsamn

packages/payload/src/folders/utils/formatFolderOrDocumentItem.ts

@@ -30,15 +30,17 @@ export function formatFolderOrDocumentItem({
   if (isUpload) {
     itemValue.filename = value.filename
     itemValue.mimeType = value.mimeType
-    itemValue.url = isImage(value.mimeType)
-      ? getBestFitFromSizes({
-          sizes: value.sizes,
-          targetSizeMax: 520,
-          targetSizeMin: 300,
-          url: value.url,
-          width: value.width,
-        })
-      : undefined
+    itemValue.url =
+      value.thumbnailURL ||
+      (isImage(value.mimeType)
+        ? getBestFitFromSizes({
+            sizes: value.sizes,
+            targetSizeMax: 520,
+            targetSizeMin: 300,
+            url: value.url,
+            width: value.width,
+          })
+        : undefined)
   }
 
   return {

test/folders/collections/Media/index.ts

@@ -2,7 +2,19 @@ import type { CollectionConfig } from 'payload'
 
 export const Media: CollectionConfig = {
   slug: 'media',
-  upload: true,
+  upload: {
+    adminThumbnail: ({ doc }) => {
+      if (doc.testAdminThumbnail && typeof doc.testAdminThumbnail === 'string') {
+        return doc.testAdminThumbnail
+      }
+      return null
+    },
+  },
   folders: true,
-  fields: [],
+  fields: [
+    {
+      name: 'testAdminThumbnail',
+      type: 'text',
+    },
+  ],
 }