Add libaconfig_python_proto target for Mobly host-based tests

Bug: 297431521
Test: unit tests (mobly_device_flags_test)
Change-Id: Ic377cb7c6f651033145a14c83c987e6d779cca6b
diff --git a/tools/aconfig/Android.bp b/tools/aconfig/Android.bp
index 296091d..28bf8a5 100644
--- a/tools/aconfig/Android.bp
+++ b/tools/aconfig/Android.bp
@@ -24,6 +24,14 @@
     },
 }
 
+python_library_host {
+    name: "libaconfig_python_proto",
+    srcs: ["protos/aconfig.proto"],
+    proto: {
+        canonical_path_from_root: false,
+    },
+}
+
 // host binary: aconfig
 
 rust_protobuf_host {