Update @github/copilot to 1.0.70 (#1962)

* Update @github/copilot to 1.0.70

- Updated nodejs and test harness dependencies
- Re-ran code generators
- Formatted generated code

* Fix generated C# leading underscore names

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Stephen Toub <stoub@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: 3 people