Refactor data module to enhance modularity and maintainability

- Extracted `OHLCVData` and validation logic into a new `common/ohlcv_data.py` module, promoting better organization and reusability.
- Updated `BaseDataCollector` to utilize the new `validate_ohlcv_data` function for improved data validation, enhancing code clarity and maintainability.
- Refactored imports in `data/__init__.py` to reflect the new structure, ensuring consistent access to common data types and exceptions.
- Removed redundant data validation logic from `BaseDataCollector`, streamlining its responsibilities.
- Added unit tests for `OHLCVData` and validation functions to ensure correctness and reliability.

These changes improve the architecture of the data module, aligning with project standards for maintainability and performance.

docs/modules/services/data_collection_service.md

@@ -26,10 +26,13 @@ This architecture allows for high scalability and fault tolerance.
 
 - **Location**: `data/exchanges/okx/collector.py`
 - **Responsibilities**:
-    - Connects to the OKX WebSocket API
-    - Subscribes to real-time data channels
-    - Processes and standardizes incoming data
-    - Stores data in the database
+    - Inherits from `BaseDataCollector` and implements exchange-specific data collection logic.
+    - Utilizes `ConnectionManager` for robust WebSocket connection management.
+    - Leverages `CollectorStateAndTelemetry` for internal status, health, and logging.
+    - Uses `CallbackDispatcher` to notify registered consumers of processed data.
+    - Subscribes to real-time data channels specific to OKX.
+    - Processes and standardizes incoming OKX data before dispatching.
+    - Stores processed data in the database.
 
 ## Configuration