Recompile STL sources when building tests

This CL works around b/240432457 by recompiling the sources of
PlatformComposeSceneTransitionLayout when compiling the associated tests
so that we can access internal members without polluting the public API.

Bug: 240432457
Test: atest PlatformComposeSceneTransitionLayoutTests
Flag: NA
Change-Id: I4ffceda155e836e360a2d8f562e2e3c43da8bbf0
diff --git a/packages/SystemUI/compose/scene/Android.bp b/packages/SystemUI/compose/scene/Android.bp
index 050d1d5..3424085 100644
--- a/packages/SystemUI/compose/scene/Android.bp
+++ b/packages/SystemUI/compose/scene/Android.bp
@@ -21,12 +21,19 @@
     default_applicable_licenses: ["frameworks_base_packages_SystemUI_license"],
 }
 
+filegroup {
+    name: "PlatformComposeSceneTransitionLayout-srcs",
+    srcs: [
+        "src/**/*.kt",
+    ],
+}
+
 android_library {
     name: "PlatformComposeSceneTransitionLayout",
     manifest: "AndroidManifest.xml",
 
     srcs: [
-        "src/**/*.kt",
+        ":PlatformComposeSceneTransitionLayout-srcs",
     ],
 
     static_libs: [