Enable jpeg support for graphicsmagik

Part of gitlab#207740 (closed)

Adding libjpeg-turbo, as it has a speed advantage, and has clearer notes on licensing.

License files for both libjpeg-turbo and libjpeg are included, and a note was added to the docs to comply with the libjpeg request as outlined in: https://github.com/libjpeg-turbo/libjpeg-turbo/blob/master/LICENSE.md#complying-with-the-libjpeg-turbo-licenses

No corresponding CNG change as the images still don't have graphics magick: gitlab-org/charts/gitlab#1185 (closed)