* fix(all): introduce and use iox.CopyContext
This PR is part of https://github.com/ooni/probe/issues/1417.
In https://github.com/ooni/probe-cli/pull/379 we introduced a context
aware wrapper for io.ReadAll (formerly ioutil.ReadAll).
Here we introduce a context aware wrapper for io.Copy.
* fix(humanize): more significant digits
* fix: rename humanize files to follow the common pattern
* fix aligment
* fix test
