feat: add dynamic subscription management with runtime filter updates

- Add update_subscription() for runtime filter updates without reconnection
  - BREAKING: Return subscription request from subscribe_with_request()
  - Implement Default trait for EventTypeFilter
  - Add comprehensive dynamic_subscription example

src/streaming/event_parser/common/filter.rs

@@ -2,7 +2,7 @@ use crate::streaming::event_parser::common::{
     types::EventType, ACCOUNT_EVENT_TYPES, BLOCK_EVENT_TYPES,
 };
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Default)]
 pub struct EventTypeFilter {
     pub include: Vec<EventType>,
 }