Flutter agent v1.1.16

Bug Fixes

• Fixed an issue where the NewRelicNavigationObserver would crash when handling routes without a key parameter, such as bottom sheets and modal dialogs.
• Resolved navigation tracking failures for routes that don't extend PageRoute.

Enhancements

• Improved type safety in NewRelicNavigationObserver by removing all dynamic types.
• Added support for additional route types including CupertinoPage and NoTransitionPage from go_router.
• Refactored navigation observer code for better maintainability and readability.