fix: Chart component children type

[nickofthyme]

Summary

React removed the implicit typing of children in react@17, causing the Chart component to throw a type error. This PR adds the implicit type back.

Details

I attempted to limit the allowable children that can be used in the Chart component in e14fe85. But react children types are not easy to restrict due to various cases.

When using a boolean, null or undefined value for gated rending.

return (
  <Chart>
    { showLegend && <Settings showLegend /> }
  </Chart>
)

When mapping over an array of values to components. Children are typed as (Element | Element[])[]

return (
  <Chart>
    { series.map(({ name, data }) => (
      <LineSeries
        name={name}
        data={data}
        ...
      />
    ) }
  </Chart>
)

Furthermore, the types would still allow prop-less components as children, see SO post.

Checklist

• New public API exports have been added to packages/charts/src/index.ts

[markov00]

LGTM