title: Using ag grid, try to row group by a value and display an other one
body: <p>I am new to Ag-grid, I've carefully read the doc of ag-grid but I can't find any section or explanation of what I need. So, I want to be able to group the rows with a particular field of my data (id) and display the name instead. </p>
  
  <p>As you can see on this picture I am able to group by Id but I want to group by Id and display the name instead.
  <a href="https://i.stack.imgur.com/FUAA7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FUAA7.png" alt="enter image description here"></a></p>
  
  <p>Here is my columns definition, as you can see I group by leaseId and I want to display the leaseName instead. </p>
  
  <pre><code>  columnDefs = [
      {
        headerName: 'Leases',
        showRowGroup: true,
        field: 'leaseId',
        cellRendererParams: {
          checkbox: true
        }
      },
      {
        headerName: 'Property Name',
        field: 'property.name',
        cellRendererParams: { checkbox: true },
        headerCheckboxSelection: params =&gt; this.allowSelect
      },
      {
        headerName: 'Lease Name',
        field: 'leaseName'
      },
      {
        headerName: 'Tenant Name',
        field: 'tenantName'
      },
      {
        headerName: 'Suite Name',
        field: 'suiteName'
      },
      {
        headerName: 'Commence Date',
        field: 'commenceDate'
      },
      {
        headerName: 'Commence Name',
        field: 'commenceName'
      },
      {
        headerName: 'Expiry Date',
        field: 'expiryDate'
      }
    ];
  </code></pre>
  
  <p>Any help will be nice :), I can provide a stackblitz if needed.</p>