This diff addresses another point of https://github.com/ooni/probe/issues/1956:
> - [ ] observe that we're still using a bunch of private interfaces for common interfaces such as the `Dialer`, so we can get rid of these private interfaces and always use the ones in `model`, which allows us to remove a bunch of legacy wrappers
Additional cleanups may still be possible. The more I cleanup, the more I see
there's extra legacy code we can dispose of (which seems good?).
* refactor(netx/dialer): hide implementation complexity
This follows the blueprint of `module.Config` and `nodule.New`
described at https://github.com/ooni/probe/issues/1591.
* fix: ndt7 bug where we were not using the right resolver
* fix(legacy/netx): clarify irrelevant implementation change
* fix: improve comments
* fix(hhfm): do not use dialer.New b/c it breaks it
Unclear to me why this is happening. Still, improve upon the
previous situation by adding a timeout.
It does not seem a priority to look into this issue now.
