Ability to pass scroll parent

## Use case
We are using react-data-grid list as a non-scrollable container which extends in height when there are new items loaded in a whole scrollable page environment. Since react-data-grid only tracks it's own container scroll positions/properties we lose the benefits of virtualization (and probably more stuff). That's why we need a passable ref prop which would be used for scroll tracking and enabling virtualization.

## Proposed solution
A passable parent scroll container ref prop to which scroll event listeners would be attached thus tracking parent scroll properties. I have POC fork available to demo how could this work https://github.com/JasonasIgn/react-data-grid