macOS: Fix safe area on macOS 10.14 and below

[madsmtm]

Similar to #4027, I didn't test the implementation of safe_area properly on older devices when I made it in #3890, likely after migrating that from rectangles to insets.

• Tested on all platforms changed
  • Tested on macOS 14.7.1 and macOS 10.12.6
• Added an entry to the changelog module if knowledge of this change could be valuable to users
  • This is going to go in the same release as the PR the bug was introduced in, so have not added a changelog entry.
• 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