Android: move AndroidBuildConfig to AndroidModule

[souvlakias]

Resolves #6141

Motivation

• BuildConfig was an additional trait to be extended only by AndroidAppModules, but regular Modules should have it as well
• Missing package field in the generated config
• There was no task to add custom fields

Changes

• Moved BuildConfig generation to AndroidModule.
  • It is configurable with the enableBuildConfig flag, which defaults to true (like gradle's).
• Added package name that defaults to androidNamespace
• Added a task for the config's members. (e.g. AndroidAppModule overrides this to add its applicationID

[souvlakias]

Should this get marked as deprecated instead?

[vaslabs]

it was experimental, so we can avoid duplications. But remember to update the examples

[souvlakias]

Would having a Map[String,Any] and then parse it, be better?

[vaslabs]

I think it's ok for now, but ; are missing from what I see

[souvlakias]

Some thoughts

Like in the case of viewBinding - in order to avoid having many traits - we override the generated sources based on a boolean flag. Since viewBinding is in AndroidKotlinModule there was no conflicts with BuildConfig, but if we were to support all BuildFeatures flags, things would get messy with this simple override.

I don't know if having a task like

override def generatedSources: T[Seq[PathRef]] = Task{
  super.generatedSources() ++
    Task.traverse(Seq(
        (androidGeneratedBuildConfigSources, enableBuildConfig),
		// More (task, boolean) tuples
      )) {
        case (task, enabled) =>
          if (enabled) task else Task.Anon(Seq.empty)
      }().flatten
}

(or something easier 😅) would be something that made sense.

[vaslabs]

lgtm

[vaslabs]

waiting for some build config fixes

[souvlakias]

BuildConfigs for normal (non-app) modules have different fields. (e.g. LIBRARY_PACKAGE_NAME vs APPLICATION_ID)

Ref: https://android.googlesource.com/platform/tools/base/+/refs/heads/studio-master-dev/build-system/gradle-core/src/main/java/com/android/build/gradle/tasks/GenerateBuildConfig.kt#116