chore(src/util/rb_tree): add debugging utils
chore(src/util/rb_tree): add debugging utils

fpvandoorn/lean,leanprover-community/lean,leanprover/lean,leanprover/lean,avigad/lean,leodemoura/lean,leanprover-community/lean,avigad/lean,rlewis1988/lean,leodemoura/lean,dselsam/lean,johoelzl/lean,digama0/lean,Kha/lean,leodemoura/lean,rlewis1988/lean,johoelzl/lean,avigad/lean,Kha/lean,leanprover-community/lean,leodemoura/lean,leodemoura/lean,Kha/lean,digama0/lean,Kha/lean,johoelzl/lean,leodemoura/lean,leanprover-community/lean,fpvandoorn/lean,Kha/lean,rlewis1988/lean,avigad/lean,dselsam/lean,johoelzl/lean,leanprover/lean,leanprover/lean,dselsam/lean,digama0/lean,avigad/lean,fpvandoorn/lean,dselsam/lean,rlewis1988/lean,dselsam/lean,dselsam/lean,leanprover/lean,leanprover-community/lean,leanprover-community/lean,digama0/lean,johoelzl/lean,Kha/lean,fpvandoorn/lean,johoelzl/lean,avigad/lean,fpvandoorn/lean,digama0/lean,leanprover/lean,rlewis1988/lean,fpvandoorn/lean,digama0/lean,rlewis1988/lean