Add DiscordEmbed

[puklipo]

This PR adds a class to create Embed object.

use Revolution\Laravel\Notification\DiscordWebhook\DiscordMessage;
use Revolution\Laravel\Notification\DiscordWebhook\DiscordEmbed;

    public function toDiscordWebhook(object $notifiable): DiscordMessage
    {
        return DiscordMessage::create()
                              ->embed(
                                  DiscordEmbed::make(
                                      title: 'INFO',
                                      description: $this->content,
                                      url: route('home'),
                                  )
                              );
    }