This updates kotlin, gson, AGP, and WorkManager to the latest versions.
It also updates the README to include the correct ndk version for our AGP, as specified here: developer.android.com/build/releases/gradle-plugin#compatibility
This updates flutter to 3.24.1, the latest stable version, and also updates our flutter dependencies to latest.
It targets the latest android sdk, 34, which is required if we want to publish a new version to the Google Play store.
I also needed to make a few adjustments to handle deprecations. The biggest change is that I needed to wrap the main widget in MaterialApp to avoid problems with AdaptiveSwitch in iOS.
