Remove Mavsdk and PX4 Flight Starter Project

[DJDMVP]

Remove Mavsdk and PX4 Flight Starter Project

Problem

Team is moving away from mavsdk and PX4 to dronekit and ardupilot. It would be best to remove the starter project to remove unnecessary time and setup needed for that.

Solution

Markdown and flight folders and files are updated to only include the dronekit starter project.