Reconnection Improvements, Channel Metrics, and Random Seed Support

[filipecosta90]

1. Subscription and Reconnection Metrics

• New Metric: totalSubscribedChannels tracks the number of currently subscribed channels across all subscribers, providing real-time insights into subscription activity.
• Reconnection Metric: totalConnects tracks the total number of reconnection events for enhanced visibility into reconnection patterns.

2. Improved Reconnection Logic

• Multi-Channel Handling:
  • Only unsubscribes/resubscribes additional channels (excluding the first channel) to minimize unnecessary overhead.
• Single-Channel Optimization: Logs when reconnection operations are skipped for subscribers with only one channel.
• Precise reconnection intervals now support millisecond granularity for fine-tuned performance scenarios.

3. Randomized Behavior with Deterministic Seed

• Added a --rand-seed flag to set a deterministic random seed, ensuring reproducible test scenarios.
• Randomized:
  • Channels per subscriber connection (--min-number-channels-per-subscriber, --max-number-channels-per-subscriber).
  • Reconnection intervals (--min-reconnect-interval, --max-reconnect-interval).

4. Enhanced CLI Output

• Added "Connect Rate": Displays reconnection events per second in real-time.
• Added "Active Subscriptions": Displays the total number of active channel subscriptions at any given time.
• Improved layout for clarity and readability.

5. Additional Logging

• Logs the total number of channels per subscriber and their names at startup.
• Logs when reconnection intervals are skipped or applied.