Standardize copyright file headers

[andystaples]

Adds/standardizes the missing or broken copyright file headers to the entire project. Also adds a note about it in copilot-instructions.md

[Copilot]

Pull request overview

Standardizes Python source-file copyright headers across the repo and documents the required header format in the Copilot contribution instructions.

Changes:

• Added the Microsoft/MIT two-line header (plus blank line) to various existing test, example, and library modules.
• Added new __init__.py files in several test/package directories with the standard header.
• Updated .github/copilot-instructions.md to require the standardized header for new handwritten Python files.

Reviewed changes

Copilot reviewed 44 out of 44 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/durabletask/test_worker_resiliency.py	Add standardized copyright header.
tests/durabletask/test_worker_concurrency_loop.py	Add standardized copyright header.
tests/durabletask/test_worker_concurrency_loop_async.py	Add standardized copyright header.
tests/durabletask/test_entity_executor.py	Add standardized copyright header.
tests/durabletask/test_client.py	Add standardized copyright header.
tests/durabletask/extensions/history_export/init.py	New init file with standardized copyright header.
tests/durabletask/extensions/init.py	New init file with standardized copyright header.
tests/durabletask/entities/test_entity_id_parsing.py	Add standardized copyright header.
tests/durabletask-azuremanaged/test_dts_batch_actions.py	Add standardized copyright header.
tests/durabletask-azuremanaged/test_dts_activity_sequence.py	Add standardized copyright header.
tests/durabletask-azuremanaged/entities/test_dts_function_based_entities_e2e.py	Add standardized copyright header.
tests/durabletask-azuremanaged/entities/test_dts_entity_failure_handling.py	Add standardized copyright header.
tests/durabletask-azuremanaged/entities/test_dts_class_based_entities_e2e.py	Add standardized copyright header.
tests/durabletask-azuremanaged/entities/init.py	New init file with standardized copyright header.
tests/durabletask-azuremanaged/init.py	New init file with standardized copyright header.
tests/init.py	New init file with standardized copyright header.
examples/work_item_filtering.py	Add standardized copyright header.
examples/version_aware_orchestrator.py	Add standardized copyright header.
examples/sub-orchestrations-with-fan-out-fan-in/worker.py	Add standardized copyright header.
examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py	Add standardized copyright header.
examples/sandboxes/remote_worker.py	Add standardized copyright header.
examples/sandboxes/main_app.py	Add standardized copyright header.
examples/human_interaction.py	Add standardized copyright header.
examples/fanout_fanin.py	Add standardized copyright header.
examples/entities/function_based_entity.py	Add standardized copyright header.
examples/entities/function_based_entity_actions.py	Add standardized copyright header.
examples/entities/entity_locking.py	Add standardized copyright header.
examples/entities/class_based_entity.py	Add standardized copyright header.
examples/entities/class_based_entity_actions.py	Add standardized copyright header.
examples/activity_sequence.py	Add standardized copyright header.
durabletask/internal/proto_task_hub_sidecar_service_stub.py	Add standardized copyright header.
durabletask/internal/orchestration_entity_context.py	Add standardized copyright header.
durabletask/internal/json_encode_output_exception.py	Add standardized copyright header.
durabletask/internal/exceptions.py	Add standardized copyright header.
durabletask/internal/entity_state_shim.py	Add standardized copyright header.
durabletask/entities/entity_operation_failed_exception.py	Add standardized copyright header.
durabletask/entities/entity_metadata.py	Add standardized copyright header.
durabletask/entities/entity_lock.py	Add standardized copyright header.
durabletask/entities/entity_instance_id.py	Add standardized copyright header.
durabletask/entities/entity_context.py	Add standardized copyright header.
durabletask/entities/durable_entity.py	Add standardized copyright header.
durabletask-azuremanaged/durabletask/azuremanaged/init.py	New init file with standardized copyright header.
durabletask-azuremanaged/init.py	New init file with standardized copyright header.
azure-functions-durable/azure/durable_functions/decorators/durable_app.py	New module added (includes standardized header).
.github/copilot-instructions.md	Document standardized header requirement for new handwritten Python files.