OSD: Clean up QML code
Drop unused ID, port to id-qualified property access, use icon.valid directly instead of implicitly inherited visibility.
Needs QA, I didn't test this.
Also, I'm questioning the sanity of untyped property var osdValue
and the subsequent hacks:
value: Number(osdValue)
text: !root.showingProgress && root.osdValue ? root.osdValue : ""