Allow deflua functions to receive encoded tables

[davydog187]

Currently, if you pass a table to a deflua function, there's no way to get the raw {:tref, _} from it, which is a problem if you want to mutate that table.

Provide an option where user's can configure this behavior. As for the implementation, it looks like using a {m, f, a} value for set_table_keys_dec will work here (this is what we use inside of Lua.set!/3)