Fix ADN extractor (#31275)

Fix ADN extractor (#31275)

* Rename Anime Digital Network to Animation Digital Network, animationdigitalnetwork.fr
* Update the test to an available video
* Update the decoding key of subtitles
* Keep the support of old URLs
* Add a test to match the old URL
* Reduce redundancy of the URL name
* Fix md5 ^^"
* Fix undefined _BASE
* Process HTTP error text (eg geo-block) correctly and uniformly in Py3, Py2
* Skip test for CI since geo-blocked

Signed-off-by: ache <ache@ache.one>
Co-authored-by: dirkf <fieldhouse@gmx.net>