fix(shell/lean): show progress messages only when stdout is a terminal
fix(shell/lean): show progress messages only when stdout is a terminal

leanprover/lean,Kha/lean,Kha/lean,digama0/lean,digama0/lean,dselsam/lean,fpvandoorn/lean,leanprover/lean,Kha/lean,leanprover/lean,fpvandoorn/lean,dselsam/lean,leodemoura/lean,leodemoura/lean,leanprover-community/lean,fpvandoorn/lean,leodemoura/lean,digama0/lean,fpvandoorn/lean,leodemoura/lean,dselsam/lean,leanprover/lean,leanprover-community/lean,leodemoura/lean,Kha/lean,leanprover/lean,Kha/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,fpvandoorn/lean,leanprover/lean,Kha/lean,leodemoura/lean,dselsam/lean,digama0/lean,leanprover-community/lean,digama0/lean,digama0/lean,fpvandoorn/lean,dselsam/lean,dselsam/lean