Add Support for Flutter Flavors to the Template

[Erengun]

Hello everyone,

Firstly, thank you for your interest and contributions to this Flutter boilerplate template. We've received a suggestion to add support for Flutter flavors to our template, and we think it's a great idea!

For those unfamiliar, Flutter flavors are build configurations that allow us to create separate environments for the same application using the same code base. This is particularly useful when we need to create multiple versions of an app, such as a development version, a production version, or different versions for different clients. These flavors can be customized to have different API endpoints, resources, app icons, and more, without duplicating the codebase. You can read more about it here.

Here's a brief overview of what needs to be done:

1. Set up the Environment: Define build configurations in Xcode for iOS and specify the flavor in the build command for Android.

   Example for iOS:

   project 'Runner', {
     'Debug-free' => :debug,
     'Profile-free' => :release,
     'Release-free' => :release,
   }
   

   Example for Android:

   /// iOS build command
   flutter build ios --release --flavor flavorName stage -t lib/main_flavorName.dart
   
   // android build command
   flutter build apk  --target-platform android-arm,android-arm64,android-x64 --split-per-abi --flavor flavorName -t lib/main_flavorName.dart
   

2. Define Flavor-Specific Configurations: Customize various aspects of the app, including API endpoints, resources, app icons, and more, without duplicating the codebase.

3. Testing: Run the app with the desired flavor using the flutter run command with the --flavor option.

   flutter run --flavor development --target lib/main_development.dart
   flutter run --flavor staging --target lib/main_staging.dart
   flutter run --flavor production --target lib/production.dart
   

We believe this would be a valuable addition to our template, making it more flexible and adaptable to various development scenarios. If anyone is interested in taking on this task, please feel free to comment below or submit a pull request. We appreciate all contributions and look forward to seeing this feature implemented!

Best,