Add AggregateAppFunctionInventory abstract class

Bug: 374924489
Test: ./gradlew :appfunctions:appfunctions-runtime:test
Change-Id: I948c1c484dda6b35d94f6d0bf330ae77ee1d88cf
diff --git a/appfunctions/appfunctions-runtime/build.gradle b/appfunctions/appfunctions-runtime/build.gradle
index 3b37e08..a95d75a 100644
--- a/appfunctions/appfunctions-runtime/build.gradle
+++ b/appfunctions/appfunctions-runtime/build.gradle
@@ -35,6 +35,9 @@
     // Internal dependencies
     implementation("androidx.annotation:annotation:1.9.0-rc01")
     implementation project(":appfunctions:appfunctions-common")
+
+    testImplementation(libs.junit)
+    testImplementation(libs.truth)
 }
 
 android {