Introduce ERS handler in daqpytools

[emmuhamm]

Description

See issue DUNE-DAQ/drunc#209 for details

We are planning on introducing ERS for error handling in drunc. Daqpytools is currently in the process of being integrated to drunc (see DUNE-DAQ/drunc#633).

This PR adds the ERSkafkahandlers defined in erskafka and makes them available for use in daqpytools. The logging demonstrator has been modified to include this as an example, which can be observed with the usual ers tools in dune (eg ers_subscriber_test)

Needs to go in with DUNE-DAQ/erskafka#43

Please also include instructions for how a reviewer can test your changes.

Type of change

• Documentation (non-breaking change that adds or improves the documentation)
• New feature or enhancement (non-breaking change which adds functionality)
• Optimization (non-breaking change that improves code/performance)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (whatever its nature)

Testing checklist

• Unit tests pass (e.g. dbt-build --unittest)
• Minimal system quicktest passes (pytest -s minimal_system_quick_test.py)
• Full set of integration tests pass (daqsystemtest_integtest_bundle.sh)
• Python tests pass if applicable (e.g. python -m pytest)
• Pre-commit hooks run successfully if applicable (e.g. pre-commit run --all-files)

Comments here on the testing

Further checks

• Code is commented where needed, particularly in hard-to-understand areas
• Code style is correct (dbt-build --lint, and/or see https://dune-daq-sw.readthedocs.io/en/latest/packages/styleguide/)
• If applicable, new tests have been added or an issue has been opened to tackle that in the future.
  (Indicate issue here: # (issue))

TODOs:

• Run linting