feat: add user selection and todos fetching functionality

src/app/user.service.ts

@@ -0,0 +1,26 @@
+import { Injectable } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { Observable, shareReplay } from 'rxjs';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class UserService {
+  constructor(private http: HttpClient) {}
+
+  getUsers(): Observable<any[]> {
+    return this.http.get<any[]>('https://jsonplaceholder.typicode.com/users')
+  }
+
+  getUser(id: number): Observable<any> {
+    return this.http.get<any>(`https://jsonplaceholder.typicode.com/users/${id}`)
+  }
+
+  getTodos(userId: number): Observable<any[]> {
+    return this.http.get<any[]>(`https://jsonplaceholder.typicode.com/todos?userId=${userId}`)
+  }
+
+  getTodo(id: number): Observable<any> {
+    return this.http.get<any>(`https://jsonplaceholder.typicode.com/todos/${id}`)
+  }
+}