feat(python): add local embedded connection support

[sundy-li]

Summary

• add Python local embedded connection support via a dedicated local adapter
• align local blocking query APIs around sql/query_row/query_all/query_iter/execute
• add real local embedded integration coverage in behave style
• require databend>=1.2.895 for the local extra and document the Python 3.12 setup

Testing

• python3 -m py_compile bindings/python/package/databend_driver/local.py
• python3 -m py_compile bindings/python/tests/local/steps/binding.py

[chatgpt-codex-connector]

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