Move internal modifier to the object to work around build errors

`error: cannot find symbol` on:

- `DataStoreModule.INSTANCE.providesUserPreferencesDataStore$datastore_demoDebug`
- `SyncModule.Companion.provideFirebaseMessaging$work_prodDebug()`

core/datastore/src/main/kotlin/com/google/samples/apps/nowinandroid/core/datastore/di/DataStoreModule.kt

@@ -33,15 +33,17 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
+import org.jetbrains.annotations.VisibleForTesting
 import javax.inject.Singleton
 
+@VisibleForTesting
 @Module
 @InstallIn(SingletonComponent::class)
 object DataStoreModule {
 
     @Provides
     @Singleton
-    internal fun providesUserPreferencesDataStore(
+    fun providesUserPreferencesDataStore(
         @ApplicationContext context: Context,
         @Dispatcher(IO) ioDispatcher: CoroutineDispatcher,
         @ApplicationScope scope: CoroutineScope,

sync/work/src/demo/kotlin/com/google/samples/apps/nowinandroid/sync/di/SyncModule.kt

@@ -24,7 +24,9 @@ import dagger.Binds
 import dagger.Module
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
+import org.jetbrains.annotations.VisibleForTesting
 
+@VisibleForTesting
 @Module
 @InstallIn(SingletonComponent::class)
 abstract class SyncModule {

sync/work/src/prod/kotlin/com/google/samples/apps/nowinandroid/sync/di/SyncModule.kt

@@ -28,8 +28,10 @@ import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
+import org.jetbrains.annotations.VisibleForTesting
 import javax.inject.Singleton
 
+@VisibleForTesting
 @Module
 @InstallIn(SingletonComponent::class)
 abstract class SyncModule {
@@ -43,9 +45,9 @@ abstract class SyncModule {
         syncSubscriber: FirebaseSyncSubscriber,
     ): SyncSubscriber
 
-    companion object {
+    internal companion object {
         @Provides
         @Singleton
-        internal fun provideFirebaseMessaging(): FirebaseMessaging = Firebase.messaging
+        fun provideFirebaseMessaging(): FirebaseMessaging = Firebase.messaging
     }
 }