[pretty please] allow fetching of cover art in mpris plugin from connected computer

Summary:
So from android 8 onwards it appears that fetching content from "cleartext" urls is disabled by default

https://stackoverflow.com/questions/45940861/android-8-cleartext-http-traffic-not-permitted

I have a mpris service running on my local computer which is connected to the android, that service is also serving cover art for currently playing song. Obviously I can not have a domain set for my computer on a local machine, so cover art urls look like
http://<ip>:<port>/<songid>.ext . Since this restriction was introduced into android 8, kde connect is not able to fetch the art from this url.

This is patch allows connections to raw IPs addresses as well. If there is any security issues regarding this change, I'm prepared to do more work, my suggestion would be to check if IP address in this case matches paired computer's IP address, although this would still be a bit annoying (especially since whatever malicious file can be served from a "cleartext" link as well).

Test Plan:

• start some sort of server which can serve an image on a paired computer
• create mpris Player instance on a paired computer and set the mpris:artUrl to the served address where this image is available
• open kde connect android app, select prepared player and see default cover art instead of the served image
• change artUrl to some image from the web
• check in kde connect again and see it correctly show a remote image

Reviewers: KDE Connect, nicolasfella, albertvaka

Reviewed By: KDE Connect, nicolasfella, albertvaka

Subscribers: albertvaka, nicolasfella, andyholmes, kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D21247