fix: custom endpoints with method: 'put' (#9037)

### What?
Fixes support for custom endpoints with `method: 'put'`.
Previously, this didn't work:
```ts
export default buildConfigWithDefaults({
  collections: [ ],
  endpoints: [
    {
      method: 'put',
      handler: () => new Response(),
      path: '/put',
    },
  ],
})
```

### Why?
We supported this in 2.0 and docs are saying that we can use `'put'` as
`method`
https://payloadcms.com/docs/beta/rest-api/overview#custom-endpoints

### How?
Implements the `REST_PUT` export for `@payloadcms/next/routes`, updates
all templates. Additionally, adds tests to ensure root/collection level
custom endpoints with all necessary methods execute properly.

Fixes https://github.com/payloadcms/payload/issues/8807

-->

templates/with-vercel-postgres/src/app/(payload)/api/[...slug]/route.ts

@@ -1,10 +1,18 @@
 /* THIS FILE WAS GENERATED AUTOMATICALLY BY PAYLOAD. */
 /* DO NOT MODIFY IT BECAUSE IT COULD BE REWRITTEN AT ANY TIME. */
 import config from '@payload-config'
-import { REST_DELETE, REST_GET, REST_OPTIONS, REST_PATCH, REST_POST } from '@payloadcms/next/routes'
+import {
+  REST_DELETE,
+  REST_GET,
+  REST_OPTIONS,
+  REST_PATCH,
+  REST_POST,
+  REST_PUT,
+} from '@payloadcms/next/routes'
 
 export const GET = REST_GET(config)
 export const POST = REST_POST(config)
 export const DELETE = REST_DELETE(config)
 export const PATCH = REST_PATCH(config)
+export const PUT = REST_PUT(config)
 export const OPTIONS = REST_OPTIONS(config)