Refactor Event System

[Kitt3120]

• Remove Subscription
• Remove ReceiverSubscription
• Fix wrong subscriber name used in Bot::join()
• Adapt code to use UUIDs instead of Subscriptions
• Refactoring of ArcObservable's get()
• Add missing AsRef<Event<…>> for ArcObservable

AI Summary

This pull request includes several changes to the event handling system and some minor improvements in the bot's task management. The most important changes involve the removal of the Subscription and ReceiverSubscription structs, modifications to the Event struct, and updates to the ArcObservable and EventRepeater implementations.

Event Handling System:

• src/event.rs: Removed the subscription module and its usage across the codebase.
• src/event/event.rs: Updated the subscribe_channel, subscribe_async_closure, and subscribe_closure methods to return Uuid instead of Subscription. Modified unsubscribe method to use Uuid directly. [1] [2] [3] [4] [5] [6]
• src/event/subscription.rs: Removed the Subscription and ReceiverSubscription structs entirely.

ArcObservable Improvements:

• src/event/arc_observable.rs: Simplified the get method and added an AsRef implementation for Event<Mutex<T>>. [1] [2]

EventRepeater Updates:

• src/event/event_repeater.rs: Adjusted to work with Uuid instead of Subscription for managing subscriptions. [1] [2] [3]

Bot Task Management:

• src/bot.rs: Added task ID handling and improved the subscription mechanism for status change events. [1] [2]

[Murasko]

idot check done, lgtm