feat: Add multiprocessing dict and sync execution for begin/end window

- Introduced `MonitoringProcessState` dataclass to handle each multiprocessing process.
- Added `sync_execution` parameter to `begin_window` and `end_window` methods in `Metric` and its subclasses.
- Updated `EnergyHistogram`, `EnergyCumulativeCounter`, and `PowerGauge` to handle `sync_execution` dynamically.
- Modified `energy_monitoring_loop` and `power_monitoring_loop` to include process-safe handling.
- Improved process cleanup and error handling for monitoring windows.