display WP numbers on planner screen

when planning a mission it is frustrating that the WP numbers are not displayed on the planning screen. When you have a lot of waypoints (eg. 300 or more) then hunting for the WP is slow
can we always display the WP number in the green tear-drop on the planning screen?

Start by running Mission Planner and locating the planning-screen code that renders the green waypoint markers, using the issue screenshot to identify the relevant view or renderer. Verify the behavior with a mission containing many waypoints; done means every green tear-drop consistently displays its waypoint number, including at least 300 waypoints.

Written by the indexing model from the issue text.