feat(frontends/lean): automatically import lua modules imported by imported lean files
feat(frontends/lean): automatically import lua modules imported by imported lean files

Signed-off-by: Leonardo de Moura <7610bae85f2b530654cc716772f1fe653373e892@microsoft.com>

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