I added a new embed type, for desmos graphing calculator
(https://www.desmos.com/calculator) that uses their supported embed URL.
I added an icon, the new embed shape, and created tests for it.
https://github.com/tldraw/tldraw/assets/111339712/acc1a6b0-2551-4f25-8f85-20e6f829930e
### Change Type
<!-- ❗ Please select a 'Scope' label ❗️ -->
- [ ] `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
- [x] `feature` — New feature
- [ ] `improvement` — Improving existing features
- [ ] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [x] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [ ] `dunno` — I don't know
### Test Plan
1. Add links for desmos graphing calculator (e.g.
https://www.desmos.com/calculator/4wa2im6u31) by either pasting or using
the insert embed menu.
### Release Notes
- (feature) add desmos embed
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Co-authored-by: Steve Ruiz <steveruizok@gmail.com>
