This is the result of this discussion:
  https://github.com/openwrt/packages/issues/8285

`urllib.request` requires the `email` module/lib, which was part of
python3-light.
This change moves the Lib/urllib folder from the python3-light into it's
own package, making it lighter. At least this way, users that want `urllib`
(on top of `python3-light`) will be forced to install it via opkg and this
will make sure `python3-email` gets installed as well.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>