I don't think the semantics of set_decorations really match with the intent of wanting to hide the status bar. On desktop platforms for example, fullscreen windows are expected to automatically get their decorations disabled. On iOS however, all windows are fullscreen but the status bar is still enabled by default. It's also a common use case to have a regular windowed application (with decorations!) on desktop platforms, but to also hide the status bar on iOS. It looks confusing to have the set_decorations call be only invoked for iOS. This pull request makes set_decorations a no-op on iOS and adds a new extension function set_prefers_status_bar_hidden to WindowExtIOS and with_prefers_status_bar_hidden to WindowBuilderExtIOS.

• Tested on all platforms changed
• Compilation warnings were addressed
• cargo fmt has been run on this branch
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality
• Updated feature matrix, if new features were added or implemented