main: Ressurect old "channel" icon
Prior to GNOME 42, the unknown channel icon looked like a TV (eg. a screen with an aerial). While that's not how TV look now, that's currently our best way to represent a "channel".
Prior to GNOME 42, the unknown channel icon looked like a TV (eg. a screen with an aerial). While that's not how TV look now, that's currently our best way to represent a "channel".