Add a minimal CLI functionality to urllib.request

[Nineteendo (Nice Zombies)]

The discussion about the random module linked above. I probably had this comment in mind:

Command-line interface for the `random` module

Personally I don’t think the stdlib shoud also be the provider of basic command-line utilities spread out over many modules as more-or-less official and supported __main__ blocks. These can be provided by a coreutils package installed in the OS, or the shell itself (sh-like like busybox, or inventing its own language like xonsh or ipython), or one PyPI package.