This PR adds a custom selection UI example.
It also fixes a bug with pageToScreen and adds a
`getSelectionRotatedScreenBounds` method.
### Change Type
- [ ] `patch` — Bug fix
- [x] `minor` — New feature
- [ ] `major` — Breaking change
- [ ] `dependencies` — Changes to package dependencies[^1]
- [ ] `documentation` — Changes to the documentation only[^2]
- [ ] `tests` — Changes to any test code only[^2]
- [ ] `internal` — Any other changes that don't affect the published
package[^2]
- [ ] I don't know
[^1]: publishes a `patch` release, for devDependencies use `internal`
[^2]: will not publish a new version
### Release Notes
- Adds selection UI example.
- Adds `Editor.getSelectionRotatedScreenBounds` method
- Fixes a bug with `pageToScreen`.
4bd1a31721