Expose `usePreloadAssets` and make sure the exploded/sublibraries
examples uses it. Before this change, fonts weren't loaded correctly for
the exploded example.
### Change Type
- [x] `sdk` — Changes the tldraw SDK
- [x] `docs` — Changes to the documentation, examples, or templates.
- [x] `bugfix` — Bug fix
This PR adds a custom static assets example.
It also:
- extracts preloadFont into a async function to make custom preloading
easier
- accounts for file-based formats
### Change Type
- [x] `minor` — New feature
### Test Plan
1. Test the example.
### Release Notes
- Docs, added custom static assets example.
This PR adds a custom tool example, the `Screenshot Tool`.
It demonstrates how a user can create a custom tool together with custom
tool UI.
### Change Type
- [x] `minor` — New feature
### Test Plan
1. Use the screenshot example
### Release Notes
- adds ScreenshotTool custom tool example
- improvements and new exports related to copying and exporting images /
files
- loosens up types around icons and translations
- moving `StateNode.isActive` into an atom
- adding `Editor.path`
alex