Makes separate target for common testing library

Bug: b/297021618
Test: atest ThemePickerTests, WallpaperPickerGoogleTests
Change-Id: I73b5567e04622dc54cea09c17518e75903daf577
diff --git a/tests/common/Android.bp b/tests/common/Android.bp
index 2904fad..d488ee4 100644
--- a/tests/common/Android.bp
+++ b/tests/common/Android.bp
@@ -23,7 +23,7 @@
 android_library {
     name: "ThemePickerTestLib",
 
-    defaults: ["ThemePicker_defaults"],
+    defaults: ["ThemePicker_common_defaults"],
     srcs: [
         "src/com/android/customization/testing/**/*.java",
         "src/com/android/customization/testing/**/*.kt",
diff --git a/tests/common/src/com/android/customization/testing/TestCustomizationInjector.kt b/tests/common/src/com/android/customization/testing/TestCustomizationInjector.kt
index 0f52024..e610818 100644
--- a/tests/common/src/com/android/customization/testing/TestCustomizationInjector.kt
+++ b/tests/common/src/com/android/customization/testing/TestCustomizationInjector.kt
@@ -27,7 +27,7 @@
 import javax.inject.Singleton
 
 @Singleton
-class TestCustomizationInjector @Inject constructor() : TestInjector(), CustomizationInjector {
+open class TestCustomizationInjector @Inject constructor() : TestInjector(), CustomizationInjector {
     private var customizationPrefs: CustomizationPreferences? = null
     private var themeManager: ThemeManager? = null
     private var themesUserEventLogger: ThemesUserEventLogger? = null