Small improvements for better developer experience:

• Skeleton block no longer reserves additional space on Service Studio preview. No runtime changes.
• Demo no longer blocks main thread execution to artificially wait for a result

Besides the "IsReady" flag, now you can also have manual control over the skeleton animation by calling:

• Skeleton_Start
• Skeleton_Stop

Improved demo to show different types of possible usages. Added "Try now"

• Added data attributes so you can better target some elements
• Fixed an issue that caused the screen reader message to appear if the Skeleton was used inside a form
• Removed the default value of `SkeletonOptions.ScreenReaderMessage`