[AutoDiff] Add tests exercising zero derivative of Array.DifferentiableView.+ and .move
[AutoDiff] Add tests exercising zero derivative of Array.DifferentiableView.+ and .move

Tests for false positive precondition triggered by a .zero gradient, i.e. empty [] array, back-propagated through concatenation and move methods
Implements a simplified reproducer of SR-14297

ahoppen/swift,atrick/swift,atrick/swift,atrick/swift,roambotics/swift,gregomni/swift,ahoppen/swift,tkremenek/swift,hooman/swift,roambotics/swift,gregomni/swift,gregomni/swift,benlangmuir/swift,tkremenek/swift,gregomni/swift,tkremenek/swift,xwu/swift,glessard/swift,atrick/swift,rudkx/swift,benlangmuir/swift,hooman/swift,hooman/swift,xwu/swift,glessard/swift,hooman/swift,glessard/swift,rudkx/swift,JGiola/swift,JGiola/swift,parkera/swift,apple/swift,atrick/swift,ahoppen/swift,benlangmuir/swift,parkera/swift,parkera/swift,tkremenek/swift,xwu/swift,rudkx/swift,roambotics/swift,parkera/swift,xwu/swift,hooman/swift,hooman/swift,apple/swift,parkera/swift,ahoppen/swift,benlangmuir/swift,xwu/swift,JGiola/swift,parkera/swift,benlangmuir/swift,glessard/swift,hooman/swift,tkremenek/swift,JGiola/swift,atrick/swift,parkera/swift,parkera/swift,apple/swift,roambotics/swift,roambotics/swift,xwu/swift,xwu/swift,rudkx/swift,glessard/swift,roambotics/swift,apple/swift,gregomni/swift,tkremenek/swift,tkremenek/swift,apple/swift,gregomni/swift,ahoppen/swift,JGiola/swift,ahoppen/swift,benlangmuir/swift,apple/swift,JGiola/swift,rudkx/swift,rudkx/swift,glessard/swift