## Description
This PR continues the refactoring of `netx` under the following principles:
1. do not break the rest of the tree and do not engage in extensive tree-wide refactoring yet
2. move under `netxlite` clearly related subpackages (e.g., `iox`, `netxmocks`)
3. move into `internal/netxlite/internal` stuff that is clearly private of `netxlite`
4. hide implementation details in `netxlite` pending new factories
5. refactor `tls` code in `netxlite` to clearly separate `crypto/tls` code from `utls` code
After each commit, I run `go test -short -race ./...` locally. Each individual commit explains what it does. I will squash, but this operation will preserve the original commit titles, so this will give further insight on each step.
## Commits
* refactor: rename netxmocks -> netxlite/mocks
Part of https://github.com/ooni/probe/issues/1591
* refactor: rename quicx -> netxlite/quicx
See https://github.com/ooni/probe/issues/1591
* refactor: rename iox -> netxlite/iox
Regenerate sources and make sure the tests pass.
See https://github.com/ooni/probe/issues/1591.
* refactor(iox): move MockableReader to netxlite/mocks
See https://github.com/ooni/probe/issues/1591
* refactor(netxlite): generator is an implementation detail
See https://github.com/ooni/probe/issues/1591
* refactor(netxlite): separate tls and utls code
See https://github.com/ooni/probe/issues/1591
* refactor(netxlite): hide most types but keep old names as legacy
With this change we avoid breaking the rest of the tree, but we start
hiding some implementation details a bit. Factories will follow.
See https://github.com/ooni/probe/issues/1591
* fix(all): introduce and use iox.ReadAllContext
This improvement over the ioutil.ReadAll utility returns early
if the context expires. This enables us to unblock stuck code in
case there's censorship confounding the TCP stack.
See https://github.com/ooni/probe/issues/1417.
Compared to the functionality postulated in the above mentioned
issue, I choose to be more generic and separate limiting the
maximum body size (not implemented here) from using the context
to return early when reading a body (or any other reader).
After implementing iox.ReadAllContext, I made sure we always
use it everywhere in the tree instead of ioutil.ReadAll.
This includes many parts of the codebase where in theory we don't
need iox.ReadAllContext. Though, changing all the places makes
checking whether we're not using ioutil.ReadAll where we should
not be using it easy: `git grep` should return no lines.
* Update internal/iox/iox_test.go
* fix(ndt7): treat context errors as non-errors
The rationale is explained by the comment documenting reduceErr.
* Update internal/engine/experiment/ndt7/download.go
* feat: use go1.16 embedding for resources
We want to embed everything that can be easily embedded. We should, at a
minimum, replace the downloading of resources and bindata.
Ref: https://github.com/ooni/probe/issues/1367.
* fix: get rid of bindata and use go embed instead
* fix: start unbreaking some automatic tests
* fix: fetch resources as part of the mobile build
* fix: convert more stuff to go1.16
I still expect many breakages, but we'll fix them.
* fix: make the windows CI green
* fix: get resources before running QA
* fix: go1.16 uses modules by default
* hopefully fix all other outstanding issues
* fix(QA/telegram.py): add another DC IP address
* Apply suggestions from code review
