Add New Select Component

Based on the design in #2557, add or update the `Select` component and any dependencies of this component to the project. Feel free to use [this CodeSandbox](https://codesandbox.io/s/netlify-cms-editor-design-j1cg3) for reference.

- [x] Update or add component to project
- [x] Add to Storybook
- [ ] Replace and use new component throughout project
- [ ] Write component tests
- [ ] Ensure tests pass
- [ ] Open a pull request

Start by locating the existing Select component and its Storybook entry, then compare them with the design in #2557 and the linked CodeSandbox. Check how the component is used throughout the project and identify the relevant test location. Done means the new Select is used across the project, component tests are added, and the test suite passes.

Written by the indexing model from the issue text.