3-way merge: Dropdown in the results view

The result view code lens, the first segment summarozed the action taken: `Incoming + Current`, `Incoming`, 'No Changes' `Manual Resolution`  The first segment should become a drop-down, that shows all the states and allows to select one. This would allow me to do all the action right in the results view. No need to click in the Incoming or Outgoing view. Visually, all that's needed is a little down arrow after the label that opens a context menu.