Function fly_inner_default_goto

fn fly_inner_default_goto(
    ctx: &mut NpcCtx<'_, '_>,
    wpos: Vec3<f32>,
    speed_factor: f32,
    height_offset: f32,
    with_terrain_following: bool,
    direction_override: Option<Dir>,
    flight_mode: FlightMode,
)

The normal controller movement action of the airship. Called from fly_airship_inner() for cases that do not mean the airship is avoiding the airship ahead of it on the route.