Added user registration call

web/services/UserService.ts

@@ -0,0 +1,29 @@
+const URL_CHAT_REGISTRATION = `http://localhost:8080/api/chat/register`;
+
+interface UserRegistrationResponse {
+  id: string;
+  accessToken: string;
+  displayName: string;
+}
+
+class UserService {
+  registerUser(username: string): Promise<UserRegistrationResponse> {
+    const options = {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({ displayName: username }),
+    };
+  
+    try {
+      const response = await fetch(URL_CHAT_REGISTRATION, options);
+      const result = await response.json();
+      return result;
+    } catch (e) {
+      console.error(e);
+    }
+
+    return null;
+  }
+}