[Long-Term Plan] Moving Forward with the React Hooks API

**Problem description**:

### Medium Term Plan

This should be our 6-12 month development plan for `downshift-js`. I think its API is a great success in providing accessibility and functionality to React Components. We should continue to improve the library in terms of bugfixes, types and features:

- [ ] Migrate hooks API to Typescript.
- [ ] Mark `` as deprecated.
- [ ] Remove ``.
- [ ] Create `useTagList` to replace `useMultipleSelection`.
- [ ] Create `useMultipleSelect` and `useMultipleCombobox` for better usage experience. Should be based on `useSelect`, `useCombobox` and `useTaglist`.
- [ ] Deprecate `useMultipleSelection`.
- [ ] Remove `useMultipleSelection`.
- [ ] Implement hooks for other components using a similar API. Suggestions: `useCarousel`, `useTree`, `useMenu`. Submit your proposals.
- [x] Migrate `useCombobox` to ARIA 1.2 specification. Remove `getComboboxProps`. Update examples.

### Comments

It's not definitive so I am looking for feedback in terms of prioritisation and features.