Update @github/copilot to 1.0.55 (#1484)

* Update @github/copilot to 1.0.55

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

* Fix Rust model switch request initialization

Use generated defaults when constructing ModelSwitchToRequest so optional fields added by schema updates do not break Rust builds.

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

---------

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 <223556219+Copilot@users.noreply.github.com>

Author: 3 people