Respect runArgs for dev containers (#53931)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #53503

Release Notes:

- Fixed gap where runArgs were not respected when specified in
devcontainer.json
c2736df3c7KyleBarton committed on 4/15/2026, 3:24:34 PM· committed by GitHubparent13185d6
2 files changedLine totals unavailable