Add support for charts to the extension API
Created by: felixfbecker
Adds support for charts in the extension API. It basically exposes a declarative, object literal API over recharts. I'm not 100% sure about all API aspects but am happy enough with this version to ship it for experimentation
Example usages:
- Line charts: https://github.com/sourcegraph/sourcegraph-search-insights
- Pie charts: https://github.com/codecov/sourcegraph-codecov/pull/52
Testing strategy: Storybooks.
Closes #10018