Expose MultiPostProcessor for testing (facebook#54296)

Summary:
Pull Request resolved: facebook#54296

Changelog: [Internal]

Reviewed By: lenaic

Differential Revision: D85624761

fbshipit-source-id: 3adf5edafe7ed8bf416048a347a1fd9e60bfea2a

Author: christophpurrer

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/image/MultiPostprocessor.kt

@@ -18,7 +18,7 @@ import java.util.LinkedList
 internal class MultiPostprocessor private constructor(postprocessors: List<Postprocessor>) :
     Postprocessor {
 
-  private val postprocessors: List<Postprocessor> = LinkedList(postprocessors)
+  internal val postprocessors: List<Postprocessor> = LinkedList(postprocessors)
 
   override fun getName(): String = "MultiPostProcessor (${postprocessors.joinToString(",")})"