This diff implements the first two cleanups defined at https://github.com/ooni/probe/issues/1956:
> - [ ] observe that `netxlite` and `netx` differ in error wrapping only in the way in which we set `ErrWrapper.Operation`. Observe that the code using `netxlite` does not care about such a field. Therefore, we can modify `netxlite` to set such a field using the code of `netx` and we can remove `netx` specific code for errors (which currently lives inside of the `./internal/engine/legacy/errorsx` package
>
> - [ ] after we've done the previous cleanup, we can make all the classifiers code private, since there's no code outside `netxlite` that needs them
A subsequent diff will address the remaining cleanup.
While there, notice that there are failing, unrelated obfs4 tests, so disable them in short mode. (I am confident these tests are unrelated because they fail for me when running test locally from the `master` branch.)
1. introduce implementations of HTTPTransport and HTTPClient
that apply an error wrapping policy using the constructor
for a generic top-level error wrapper
2. make sure we use the implementations in point 1 when we
are constructing HTTPTransport and HTTPClient
3. make sure we apply error wrapping using the constructor for
a generic top-level error wrapper when reading bodies
4. acknowledge that error wrapping would be broken if we do
not return the same classification _and_ operation when we wrap
an already wrapped error, so fix the to code to do that
5. acknowledge that the classifiers already deal with preserving
the error string and explain why this is a quirk and why we
cannot remove it right now and what needs to happen to safely
remove this quirk from the codebase
Closes https://github.com/ooni/probe/issues/1860
When preparing a tutorial for netxlite, I figured it is easier
to tell people "hey, this is the package you should use for all
low-level networking stuff" rather than introducing people to
a set of packages working together where some piece of functionality
is here and some other piece is there.
Part of https://github.com/ooni/probe/issues/1591
