feat(storage-vercel-blob): allow fallback to disk if token not set (#10005)

Previously with `@payloadcms/plugin-storage-blob`, if token was not set,
the plugin would throw an error. This caused a less-than-ideal developer
experience.

With this change, if the `token` value is undefined:
- Local storage will be used as a fallback
- The error will no longer be thrown.

test/storage-vercel-blob/collections/Media.ts

@@ -3,7 +3,6 @@ import type { CollectionConfig } from 'payload'
 export const Media: CollectionConfig = {
   slug: 'media',
   upload: {
-    disableLocalStorage: true,
     resizeOptions: {
       position: 'center',
       width: 200,