[feature] Add firmware upgrader websocket routes #484

[Adityashandilya555]

Adds websocket routes for the OpenWISP firmware upgrader module when USE_OPENWISP_FIRMWARE environment variable is enabled.

This enables real-time upgrade progress tracking for:

• Individual upgrade operations
• Batch upgrade operations
• Device-specific upgrade progress

Checklist

• [ ] I have read the OpenWISP Contributing Guidelines.
• [ ] I have manually tested the changes proposed in this pull request.
• [ ] I have written new test cases for new code and/or updated existing tests for changes to existing code.
• [ ] I have updated the documentation.

Reference to Existing Issue

Closes #484.

Description of Changes

Modified images/common/openwisp/asgi.py to include firmware upgrader websocket routes Please describe these changes.

Screenshot

Please include any relevant screenshots.