Widgets in Talk: Show Pictures from more sources

[jakobroehrl]

Follow up: #33494
e.g. from Blog Articles and from invidio.us (youtube is working great):

[szaimen]

cc @juliushaertl

[juliusknorr]

The default image is taken from open graph data, so this is up to the website to set an image which will then be used for the preview: https://ogp.me

https://www.opengraph.xyz is quite helpful for testing if a website supports it.

Our website seems to work fine at least now with the blogpost you linked: