Start building a UI component library as part of coko client

We need to add ant-based components as part of the coko client library. There's quite a few components that are ready for reuse in the hhmi repo (here).

The task here is two-fold:

• Add coko storybook to the repo
• Move only the button component from hhmi to coko client

Components should always have a corresponding story, so grab the story from hhmi as well.

The end result should be that we should be able to run storybook from this repo and it should display one component inside it (the aforementioned button component).