refactor: replace signIn callback with signIn event, adjust getUserByEmail in adapter to check provider (#1223)

* refactor: replace signIn callback with signIn event, adjust getUserByEmail in adapter to check provider

* test: adjusting tests for adapter and events

* docs: add comments for unknown auth provider

* fix: missing dayjs import

packages/auth/next.ts

@@ -2,7 +2,7 @@ import { cache } from "react";
 
 import { createConfiguration } from "./configuration";
 
-const { auth: defaultAuth } = createConfiguration(false, null);
+const { auth: defaultAuth } = createConfiguration("unknown", null);
 
 /**
  * This is the main way to get session data for your RSCs.