Currently, we only use native `structuredClone` in the browser, falling
back to `JSON.parse(JSON.stringify(...))` elsewhere, despite Node
supporting `structuredClone` [since
v17](https://developer.mozilla.org/en-US/docs/Web/API/structuredClone)
and Cloudflare Workers supporting it [since
2022](https://blog.cloudflare.com/standards-compliant-workers-api/).
This PR adjusts our shim to use the native `structuredClone` on all
platforms, if available.
Additionally, `jsdom` doesn't implement `structuredClone`, a bug [open
since 2022](https://github.com/jsdom/jsdom/issues/3363). This PR patches
`jsdom` environment in all packages/apps that use it for tests.
Also includes a driveby removal of `deepCopy`, a function that is
strictly inferior to `structuredClone`.
### Change Type
<!-- ❗ Please select a 'Scope' label ❗️ -->
- [x] `sdk` — Changes the tldraw SDK
- [x] `dotcom` — Changes the tldraw.com web app
- [ ] `docs` — Changes to the documentation, examples, or templates.
- [ ] `vs code` — Changes to the vscode plugin
- [ ] `internal` — Does not affect user-facing stuff
<!-- ❗ Please select a 'Type' label ❗️ -->
- [ ] `bugfix` — Bug fix
- [ ] `feature` — New feature
- [x] `improvement` — Improving existing features
- [x] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [ ] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [ ] `dunno` — I don't know
### Test Plan
1. A smoke test would be enough
- [ ] Unit Tests
- [x] End to end tests
