Update api_service to use WebSockets

### Describe your improvement idea or feature request

The new JobQueue system in CCSync does not directly tell the status of the Job or its response, but uses a WebSocket instead.
Integrate this to the `api_service.dart` using [web sockets library in Flutter](https://pub.dev/packages/web_socket_channel).

### How would you like to see it implemented?

1. The user adds/deletes/marks as completed, deleted just like earlier, but
2. Websocket is used to get the message/status and shows the relevant Snackbar
Similar to [this](https://github.com/CCExtractor/ccsync/pull/71)

### Put here any screenshots or videos (optional)

_No response_

### How can we contact you (optional)

Github/Slack

### Would you like to work on this issue?

None

### By submitting this issue, I have confirmed that:

- [X] I have starred the repo ⭐ and watched 👀 it on GitHub and followed the contribution guidelines.

Read api_service.dart and compare the proposed WebSocket flow with pull request #71, using the web_socket_channel library referenced in the issue. Verify that add, delete, and complete actions still work, and that JobQueue status or response messages produce the relevant Snackbar.

Scritto dal modello di indicizzazione a partire dal testo della issue.