Live activity improvements

[10nas]

• Add back live previews for the simple live activity view.
• Refactor LiveActivityAttributes.ContentState.
• Change LiveActivity structure for readability.
• Fix cases where text got clipped in the simple live activity. Live previews are really helpful to find these kinds of issues. Please don't delete the live previews again in the future.
• Add a disclaimer "Live Activity Expired" when the live activity expires on the lock screen. Important improvement that has also been requested on Discord before.
• Delete unused file in the live activity folder.

[dnzxy]

I did not see the clipping that was supposed to be fixed either before or after applying the patch.

If you want to reproduce clipping, simulate a 3 digit glucose with a double arrow up, that should be clipped to something like 10… instead of 100 <arrow> (before this fix).