Add Facebook Integration

This issue tracks the implementation of an integration for **Facebook** in Elsa Workflows. The module should allow workflows to interact with Facebook, supporting retrieving user content and monitoring media uploads.

## **Tasks**
- [ ] Create a new module: `Elsa.Integrations.Facebook`
- [ ] Implement **Workflow Activities**:
- [ ] **ListPages** - Returns user pages.
- [ ] **ListPhotos** - Returns user photos.
- [ ] **ListVideos** - Returns user videos.
- [ ] **WatchPhotos** - Triggers when a new photo is added.
- [ ] **WatchVideos** - Triggers when a new video is added.

- [ ] Add Unit Tests
- [ ] Add Documentation (`README.md`)

## **References**
- 📖 [Facebook Graph API Docs](https://developers.facebook.com/docs/graph-api)
- 🛠️ [Facebook Developer Resources](https://developers.facebook.com/)

## **Notes**
- This should follow the standard structure used for Elsa Integrations.
- The integration should support authentication via OAuth 2.0.

## **Contributor Guidelines**
If you're interested in working on this issue:

1. Comment below to claim it.
2. Follow the [CONTRIBUTING.md](https://github.com/elsa-workflows/elsa-integrations/blob/main/CONTRIBUTING.md) guide.
3. Submit a PR referencing this issue.