Increases the minimum macOS deployment target from macOS 10.13 (High Sierra) to 10.14 (Mojave) in the macOS app templates.

Includes:
* Update migration for macOS 10.11 apps to upgrade to 10.14
* Adds migration for macOS 10.13 apps to upgrade to 10.14
* Apply migration to all examples, and integration tests

This does not increase version in the plugin templates since those will need to wait until the 10.14 framework rolls to stable channel, so new plugins can build with apps created with `flutter create` on stable channel.

Issue: https://github.com/flutter/flutter/issues/114445
See RFC: http://flutter.dev/go/flutter-drop-macOS-10.13-2022-q4
See previous patch: https://github.com/flutter/flutter/pull/107689

This reverts commit bfe9c598.

This reverts commit 31e33647.

This change updates the platform runners in the benchmarks subdir.

I've attempted to replace the entire group with new code as if the project were recreated with flutter create so that they don't become a Frankenstein of minor changes to make it work again, but just plain old generated code that can be replaced and updated in place.