add flat file impl with find by email, save not implemented yet

src/User/FlatFileUserRepository.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace FreightQuote\User;
+
+class FlatFileUserRepository implements UserRepository
+{
+    private string $pathToUserFile = __DIR__.'/../../storage/users.json';
+
+    public function findByEmail(string $email): ?User
+    {
+        $json = file_get_contents($this->pathToUserFile);
+        $data = json_decode($json, true);
+        foreach ($data as $user) {
+            if ($user['email'] === $email) {
+                return new User($user['email'], $user['password']);
+            }
+        }
+    }
+
+    public function save(User $user): User
+    {
+    }
+}