Implement BarChart annotations feature

[jaronheard]

Is your feature request related to a problem? Please describe. The current annotations prop on the BarChart renders a hard coded annotation, based on whether the annotations prop is passed, but not dependent on the annotations value

Describe the solution you'd like The BarChart should have an annotations prop that makes sense and renders annotations

Describe alternatives you've considered The annotations prop should be removed

Additional context Should implement the feature satisfying the following:

• [ ] Sensible API in context of BarChart API
• [ ] Allows for multiple annotations
• [ ] Adds a story showing the use of the annotations prop