Add middleware and refactor admin handlers for improved functionality

- Introduced `DependenciesMiddleware` and `BlacklistMiddleware` for enhanced request handling across all routers.
- Refactored admin handlers to utilize new middleware, improving access control and error handling.
- Updated the `admin_router` to include middleware for access checks and streamlined the process of banning users.
- Enhanced the structure of admin handler imports for better organization and maintainability.
- Improved error handling in various admin functions to ensure robust user interactions.

helper_bot/handlers/group/exceptions.py

@@ -0,0 +1,11 @@
+"""Custom exceptions for group handlers"""
+
+
+class NoReplyToMessageError(Exception):
+    """Raised when admin tries to reply without selecting a message"""
+    pass
+
+
+class UserNotFoundError(Exception):
+    """Raised when user is not found in database for the given message_id"""
+    pass