Switch icon theme to Fluent icons

resources/icons/ui/end-call.png

resources/icons/ui/end-call.svg

resources/icons/ui/image-failed.svg

resources/icons/ui/lock.png

resources/icons/ui/lock@2x.png

resources/icons/ui/lowprio.png

resources/icons/ui/lowprio.svg

resources/icons/ui/lowprio@2x.png

resources/icons/ui/mail-reply.png

resources/icons/ui/microphone-mute.png

resources/icons/ui/microphone-mute.svg

resources/icons/ui/microphone-unmute.png

resources/icons/ui/microphone-unmute.svg

resources/icons/ui/options.svg

resources/icons/ui/paper-clip-outline.png

resources/icons/ui/paper-clip-outline@2x.png

resources/icons/ui/pause-symbol.png

resources/icons/ui/pause-symbol.svg

resources/icons/ui/pause-symbol@2x.png

resources/icons/ui/picture-in-picture.svg