Enable usage of svg favicons and remove imagick from iconbuilder

[szaimen]

This allows us to get rid of using imagick in iconbuilder of the theming app, which in return allows us to not enforce this requirement anymore since gd and imaginary can be used for all other tasks.

Julius found this: https://www.leereamsnyder.com/blog/favicons-in-2021#safari-does-not-fully-support-svg-icons

cc @juliushaertl

[szaimen]

also cc @nextcloud/ios

[juliusknorr]

Seems to work just fine with an svg and the mask for safari:

Now we'd need to check if there is a way to invert the svg to be filled with masking out the app icon or if the new safari icon design would be fine, but otherwise I'd say it would be a good step to get rid of imagick there.

[juliusknorr]

Would also solve #27502

[szaimen]

Great 🎉

[szaimen]

Maybe someone with a mac could look into this for 27? :)

I could help testing a PR on other platforms :)

[szaimen]

Also cc @AndyScherzinger

[AndyScherzinger]

I am not having a mac, so If it works for Julius I think we are fine.