daemon: allow per-request variables in Lua
The handlers in Lua can now store per-request variables that are automatically GC'd when the request is finished. This is useful for stateful modules, such as DNS64 that uses internal option flags for state tracking, or stats that previously couldn't be implemented in Lua
The layers can now get a variable table like so:
local vars = kres.request_t(r):vars() vars.hello = true
The variables are persisted between different layers for each request.
- Add to to basic resolve tests
Update DNS64 module
- Add to library documentation