feat!: custom views are now public by default and fixed some issues with notFound page (#8820)

This PR aims to fix a few issues with the notFound page and custom views
so it matches v2 behaviour:
- Non authorised users should always be redirected to the login page
regardless if not found or valid URL
- Previously notFound would render for non users too potentially
exposing valid but protected routes and creating a confusing workflow as
the UI was being rendered as well
- Custom views are now public by default
- in our `admin` test suite, the `/admin/public-custom-view` is
accessible to non users but
`/admin/public-custom-view/protected-nested-view` is not unless the
checkbox is true in the Settings global, there's e2e coverage for this
- Fixes https://github.com/payloadcms/payload/issues/8716

packages/next/src/utilities/initPage/index.ts

@@ -12,6 +12,7 @@ import { getPayloadHMR } from '../getPayloadHMR.js'
 import { initReq } from '../initReq.js'
 import { getRouteInfo } from './handleAdminPage.js'
 import { handleAuthRedirect } from './handleAuthRedirect.js'
+import { isCustomAdminView } from './isCustomAdminView.js'
 import { isPublicAdminRoute } from './shared.js'
 
 export const initPage = async ({
@@ -133,7 +134,8 @@ export const initPage = async ({
 
   if (
     !permissions.canAccessAdmin &&
-    !isPublicAdminRoute({ adminRoute, config: payload.config, route })
+    !isPublicAdminRoute({ adminRoute, config: payload.config, route }) &&
+    !isCustomAdminView({ adminRoute, config: payload.config, route })
   ) {
     redirectTo = handleAuthRedirect({
       config: payload.config,