* Use Xcode build configurations to drive Flutter build mode
* Proper check wrt local_engine, print error if profile mode misisng
* Remove unused code, update tests, fix template problem, update warning
* fix up warning
* add explanatory dev comment
* fix whitespace
* missing words, change lambda arrow to function body
* error indentation
* Test early exits for xcode_backend.sh
* only on macOS, use right test
* Update error messages
* case insensitive compare for build config
* Update gallery podfile
* update projects to add profile configuration
* make compatible with flavors
* add missing plist files
Generated.xcconfig is only required at build time for iOS apps. In the
flutter create project template and example apps, Generated.xcconfig was
previously marked as a resource to be bundled into the built app.