rework login page, deduplicate code by using layouts

web/src/routes/login/+layout.ts

@@ -0,0 +1,16 @@
+import type {LayoutLoad} from './$types';
+import {env} from '$env/dynamic/public';
+
+const apiUrl = env.PUBLIC_API_URL;
+
+export const load: LayoutLoad = async ({fetch}) => {
+    const response = await fetch(apiUrl + '/auth/metadata', {
+        method: 'GET',
+        headers: {
+            'Content-Type': 'application/json'
+        },
+        credentials: 'include'
+    });
+
+    return {oauthProvider: await response.json()};
+};