Re-add --public option for dev-server

Hey Webpackers!

This release re-adds the --public option, which can be useful for the dev-server, especially with Docker. WIP docs can be found at: symfony/symfony-docs#16622

To upgrade run:

yarn upgrade "@symfony/webpack-encore@^1.8.2"

Changes: v1.8.1..v1.8.2

Documentation: http://symfony.com/doc/current/frontend.html

Highlights:

Bug Fix

• #1095 - bug #1095 Revert removing public option from dev-server - @louismariegaborit

Happy packing!