title: How to copy rows from one ag-grid to second ag-grid
body: <p>I've two ag-grids on my UI. 
  Ag-grid 1 has 4 rows. Ag-grid 2 has 5 rows. Both ag-grids have same columns. 
  I want to copy all the rows from Ag-grid 2 to Ag-grid 1 on some button click.
  How can I do that?</p>
  
  <p>Expected result:
  On button click. </p>
  
  <ol>
  <li>Ag-grid 1 should have 9 rows (4 original rows and 5 rows which are copied from Ag-grid 2).</li>
  <li>Ag-grid 2 should have 0 rows</li>
  </ol>