feat: Refactor log-alert application into modular structure

- Introduced alerters package with base Alerter class and implementations for LogAlerter and GotifyAlerter.
- Created fetchers package with abstract LogFetcher class and implementations for FileLogFetcher, LokiLogFetcher, and ParseableLogFetcher.
- Added filters package with base Filter class and implementations for RegexpFilter and GeolocationFilter.
- Implemented rules package with base AlertRule class and SimpleAlertRule for alerting logic.
- Enhanced configuration handling with utilities for loading and validating JSON configuration.
- Updated logging setup for better logging management.
- Modified main application logic to utilize the new modular structure, improving maintainability and readability.
- Updated config.json and config.schema.json to reflect changes in alerting and fetching configurations.
- Added python-dateutil to requirements for date parsing functionality.

log-alert/filters/base.py

@@ -0,0 +1,20 @@
+"""Abstract base class for filters."""
+
+from abc import ABC, abstractmethod
+from typing import Dict, Any, Optional
+
+
+class Filter(ABC):
+    """Abstract base class for filters."""
+
+    @abstractmethod
+    def filter(self, log: Dict[str, Any]) -> Optional[Dict[str, Any]]:
+        """Apply filter to a log entry.
+        
+        Args:
+            log: Log entry dictionary
+            
+        Returns:
+            Modified log entry, or None if the log should be filtered out
+        """
+        pass