feat(frontends/lean/placeholder_elaborator): display instance trace header once per class-instance resolution problem
feat(frontends/lean/placeholder_elaborator): display instance trace header once per class-instance resolution problem

dselsam/lean,soonhokong/lean-windows,c-cube/lean,htzh/lean,levnach/lean,htzh/lean,digama0/lean,leanprover/lean,soonhokong/lean-osx,javra/lean,leodemoura/lean,fgdorais/lean,digama0/lean,leanprover/lean,dselsam/lean,c-cube/lean,johoelzl/lean,javra/lean,rlewis1988/lean,leanprover-community/lean,UlrikBuchholtz/lean,Kha/lean,johoelzl/lean,sp3ctum/lean,leanprover/lean,fpvandoorn/lean2,rlewis1988/lean,avigad/lean,soonhokong/lean-windows,htzh/lean,fpvandoorn/lean2,avigad/lean,leanprover/lean,soonhokong/lean-osx,fpvandoorn/lean,leanprover/lean,eigengrau/lean,avigad/lean,digama0/lean,Kha/lean,sp3ctum/lean,Kha/lean,levnach/lean,Kha/lean,soonhokong/lean-windows,johoelzl/lean,sp3ctum/lean,leanprover-community/lean,dselsam/lean,Kha/lean,dselsam/lean,eigengrau/lean,leanprover-community/lean,fpvandoorn/lean,soonhokong/lean,UlrikBuchholtz/lean,sp3ctum/lean,fgdorais/lean,avigad/lean,fgdorais/lean,htzh/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,javra/lean,dselsam/lean,eigengrau/lean,levnach/lean,soonhokong/lean-osx,avigad/lean,c-cube/lean,fpvandoorn/lean,rlewis1988/lean,fgdorais/lean,soonhokong/lean,levnach/lean,fpvandoorn/lean,leodemoura/lean,dselsam/lean,levnach/lean,c-cube/lean,leanprover-community/lean,rlewis1988/lean,fpvandoorn/lean,avigad/lean,rlewis1988/lean,fpvandoorn/lean2,leanprover/lean,fpvandoorn/lean,eigengrau/lean,fgdorais/lean,c-cube/lean,johoelzl/lean,leodemoura/lean,javra/lean,soonhokong/lean,sp3ctum/lean,soonhokong/lean,UlrikBuchholtz/lean,rlewis1988/lean,fpvandoorn/lean2,soonhokong/lean-windows,digama0/lean,soonhokong/lean-osx,johoelzl/lean,fpvandoorn/lean2,soonhokong/lean-osx,eigengrau/lean,leodemoura/lean,UlrikBuchholtz/lean,leanprover-community/lean,leodemoura/lean,htzh/lean,digama0/lean,digama0/lean,javra/lean,leanprover-community/lean,johoelzl/lean,soonhokong/lean,leodemoura/lean,fgdorais/lean,Kha/lean