Refactor Pluggables Service and add SBI support

- Removed unused import of google.protobuf.field_mask from pluggables.proto.
- Updated DigitalSubcarrierGroupState and PluggableConfig messages in pluggables.proto to include additional fields for configuration management.
- Enhanced PluggablesServiceServicerImpl to support pushing configurations to devices, including error handling and logging.
- Added new methods for translating pluggable configurations to NETCONF format in config_translator.py.
- Created CommonObjects.py and PreparePluggablesTestScenario.py for test setup and device configuration.
- Implemented comprehensive tests for creating, configuring, retrieving, and deleting pluggables with NETCONF devices in test_pluggables_with_SBI.py.
- Updated pytest.ini to include integration test marker for better test categorization.