Tauri-demo: refactor login-attempt listeners

app.ts

  get #loginElement () {
      return this.shadowRoot!.querySelector('yag-login') as HTMLElement;
  }
  #setLoginListener = () => {
      this.#loginElement.addEventListener('login-attempt', this.#handleLoginAttempt);
  }

  #unsetLoginListener = () => {
      this.#loginElement?.removeEventListener('login-attempt', this.#handleLoginAttempt);
  }

  #setViewAccordingToUserStatus = () => {

      if (!this.#authComponent!.isLoggedIn || this.#authComponent!.isLoggedIn?.() === false) {
          this.shadowRoot!.innerHTML = `<yag-login></yag-login>`;
          this.#setLoginListener();

      } else {
          this.#unsetLoginListener();

          this.shadowRoot!.innerHTML = `<yag-greeter></yag-greeter>`;
      }
  }