Add a checkbox to the Move & View panel labeled, "Double-Click to:"
Below that checkbox are two radio buttons:
( ) Teleport
( ) Auto-Pilot
You can only select one option or the other. Note - this toggle is already implemented in the Developer file menu item (in case you need it for reference).
When "Teleport" is selected users can double-click inworld to automatically teleport to that position.
When "Auto-Pilot" is selected users can double-click inworld to automatically walk towards that position. (Note: if there is an object in their way, the auto-pilot will fail - that is expected behavior for now).