Draft: [debug] add DBG_TRANSACTIONS flag and hide transactions debug by default

I've made this commit a super long time ago, it's bit quite some time that I deved on CW itself so I'm not sure how cool it is but I think it can help make debugging easier.

But I think this option does similar things than DBG_OPS but I'm not sure :/ (and that might be why I haven't push it too much)

CW debug output log is very verbose and most information is not always useful in all situation. This new flag is an attempt to make logs more useful by default while not preventing from adding this additional information when needed.