Heatmap does not implement onProjectionAreaChange event

[nickofthyme]

Describe the issue
The Heatmap does not implement the onProjectionAreaChange, it only return null for the callback.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://codesandbox.io/s/damp-currying-3qppd8?file=/src/App.tsx
2. Change size of chart
3. Notice the onProjectionAreaChange logs do not fire and if they do only return null.

Expected behaviour
Returns correct dimensions as demonstrated in here for xy charts