feat(frontends/lean/decl_cmds): generate bytecode when adding definitions
feat(frontends/lean/decl_cmds): generate bytecode when adding definitions

Remark: when the code generator fails we just generate a warning.
Reason: code generator does not support wellfounded recursion yet.

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