Check mission climb always on current mission item

[KonradRudin]

Solved Problem

There is a bug when activating a mission for checking if a climb is required. The check is performed on the inactivation_index instead of the chosen mission index. The inactivation index should only be used when infering, if a mission was interrupted during a survey, instead the climb required check should always be performed on the mission item that comes first. In addition the inactivation index should be reset, when a misison is interrupted and the user changes the current sequence as well as when the mission is reset.

Fixes #{Github issue ID}

Solution

• Make sure to use the current mission index when performing the climb check.
• Reset inactivation index when user sets current sequence of the mission is reset.

Changelog Entry

For release notes:

Bugfix Make sure the climb check at the start of a mission is performed at the current mission item.

Test coverage

• Unit/integration test: Tested in SITL gazebo-classic_standard_vtol

[sfuhrer]

Seems right to me. The original intend is still covered, as when a resume during a survey happens setMissionIndex() sets the current_seq which is then checked by the checkClimbRequired().
Hopefully we can also simplify the whole mission logic further, there's currently too any internal states to take care of.

[KonradRudin]

Yes, and the checkClimbRequired should still check the mission item even when the inactivation_index is set to -1 due to a reset.