title: How do I specify the RowNode.id in ag-grid
body: <p>I'm posting this here because this wasted a fair bit of my time today.</p>
  <p>I was trying to set the <code>RowNode.id</code> from the data in the objects I set aggrid's <code>rowData</code> property to.  meaning, I wanted to use a property on my data model to supply the built in <code>id</code> field of ag-grid's row model.  They mention this in the documentation but they don't explain how to do itp.</p>