Export framework-res raw resources to robolectric

Robolectric needs the raw resources from framework-res for now,
export them as a filegroup.

Bug: 122331577
Test: m checkbuild
Change-Id: I3981743d579c6ed1a93da81e583d565c9d8a2cba

core/res/Android.bp

@@ -39,3 +39,12 @@ android_app {
     // PRODUCT-agnostic resource data like IDs and type definitions.
     export_package_resources: true,
 }
+
+// This logic can be removed once robolectric's transition to binary resources is complete
+filegroup {
+    name: "robolectric_framework_raw_res_files",
+    srcs: [
+        "assets/**/*",
+        "res/**/*",
+    ],
+}