[generic] support for various podcast sites

[kayb94]

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What is the purpose of your pull request?

• New feature

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Description of your pull request and other information

This adds support for various german podcast sites. They all have kind of the same page layout. Including the one in the test, I verified it works with the following pages/examples:

https://logbuch-netzpolitik.de/lnp247-lastesel-mit-glasfaseranschluss
https://cre.fm/cre217-mythos-68er
https://freakshow.fm/fs214-hoert-euch-doch-mal-zu/
https://forschergeist.de/podcast/fg054-urbane-resilienz
https://raumzeit-podcast.de/2018/03/14/rz071-asteroidenabwehr/
https://fokus-europa.de/podcast/fe025-rechtspopulismus-in-europa/
https://not-safe-for-work.de/nsfw098-publikationspromiskuitaet/
https://kolophon.oreilly.de/kol017-startups/
https://der-lautsprecher.de/ls018-audioformate-fuer-podcasts
https://newz-of-the-world.com/newz088-were-gonna-miss-him-when-hes-gone/
https://diegesellschafter.metaebene.me/dg024-freiwilliges-soziales-jahr/
https://requestforcomments.de/archives/412

This closes #15872 and #15873 (this is the same, just for the generic extractor).

[kayb94]

Friendly ping, in case you forgot about the pull request @dstftw
From the other pull request it looks like other people would like this, too. Those podcasts are pretty popular here.

Kind regards
Kay