Add support for auto-generated characteristics RRO

Setting use_rro_for_product will automatically generate an RRO package
which contains resources with 'product="{PRODUCT_CHARACTERISTICS}"'. The
RRO package will be installed to /product partition. The app will be
compiled with '--product default', making the app identical to all
targets.

Motivation for this change is to minimize divergence of system.img.

Bug: 294799593
Test: boot and idmap2 dump
Change-Id: I549c2589c69eab7a1568510a7d1ff0c8a003f7ea
diff --git a/tools/Android.bp b/tools/Android.bp
index b8ab162..5c54fcf 100644
--- a/tools/Android.bp
+++ b/tools/Android.bp
@@ -96,3 +96,13 @@
         unit_test: true,
     },
 }
+
+python_binary_host {
+  name: "characteristics_rro_generator",
+  srcs: ["characteristics_rro_generator.py"],
+  version: {
+    py3: {
+      embedded_launcher: true,
+    },
+  },
+}