Add mission check land when no approach

[KonradRudin]

Solved Problem

When a VTOL is flying in air, we want to make sure that a landing is defined either by VTOL land approaches on home/rally points or the mission. Thus when uploading a new mission in air, the mission should get rejected, when it does not define a landing and there are no landing approaches defined for the safe points.

Fixes #{Github issue ID}

Solution

Add a new mission check option in MIS_TKO_LAND_REQ. This option checks, if a landing is defined, when in air and no safe point approaches are defined. While on the ground, it will use the same logic as MIS_TKO_LAND_REQ=4

Changelog Entry

For release notes:

Feature: New Mission takeoff/landing required option to check for a valid landing (either mission landing or land approaches) when in air.

Test coverage

• Unit/integration test: ...
• Simulation/hardware testing logs: https://review.px4.io/

[sfuhrer]

Works for me, and the extra RTL debugging should help as well!