Add LSPS5 event enums for webhook operations

- Introduce LSPS5ServiceEvent for LSPS-side webhook events including registration, listing, removal, and notification.
- Define LSPS5ClientEvent for handling webhook outcomes on the client (Lightning node) side.
- Outline WebhookNotificationParams enum to support notification-specific parameters.
- Improve LSPS5 event documentation and field naming
- Rename client/lsp fields to counterparty_node_id for consistent terminology
- Replace generic String types with more specific Lsps5AppName and Lsps5WebhookUrl
- Add comprehensive documentation for all events and fields
- Include format specifications (UTF-8, ISO8601) and size constraints
- Add request_id field to all relevant events for consistent request tracking
- Provide detailed descriptions of error codes and their meanings
- Use complete sentences in documentation comments

Author: martinsaposnic

lightning-liquidity/src/events/event_queue.rs

@@ -1,6 +1,5 @@
 use super::LiquidityEvent;
 use crate::sync::{Arc, Mutex};
-
 use alloc::collections::VecDeque;
 use alloc::vec::Vec;