chore(library/init/bool): add xor for Booleans
chore(library/init/bool): add xor for Booleans

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