Supports undo step generation while navigating in locked camera view. NDOF & track-pad navigation are not included for now. Actions that uses smooth view can be supported but are outside the scope of this change, includes undo push for: - VIEW3D_OT_view_pan - VIEW3D_OT_dolly - VIEW3D_OT_fly - VIEW3D_OT_move - VIEW3D_OT_rotate - VIEW3D_OT_walk - VIEW3D_OT_zoom Reviewed by: campbellbarton Ref D15345