Coroutine Local baggages for Lua

[vaastav]

Currently there is no way of specifying baggages local to a specific coroutine in lua. This would be nice to have especially for Lua servers that launch a new coroutine to handle/process a new request.

I am not sure what the best way of implementing this is. Maybe keeping a map of coroutine to baggages and having each Xtrace request pass the id of the coroutine as a parameter into the C++ side could solve this. This would mean we would need to support multiple baggages inside a single thread but there doesn't seem to be any other alternative