This PR adds a generic that we can use with `updateShapes` and
`createShapes` in order to type the partials being passed into those
methods. By default, the partials are typed as `TLUnknownShape`, which
accepts any props.
### Change Type
- [x] `minor` — New feature
### Test Plan
- [x] Unit Tests
### Release Notes
- [editor] adds an optional shape generic to `updateShapes` and
`createShapes`
ce1cf82029