aconfig: add default-permission argument for create-cache command

Aconfig set flag default permission as READ_WRITE regardless of the
release configuration. This change enables the caller of create-cache to
set the default permission for all flags, if the flag doesn't have a
value.

Test: atest aconfig.test
Bug: 294417368
Change-Id: I1ba19e1ba793cd2ae59923b136b9b50a92315ece
diff --git a/tools/aconfig/src/test.rs b/tools/aconfig/src/test.rs
index 14beb93..6c27885 100644
--- a/tools/aconfig/src/test.rs
+++ b/tools/aconfig/src/test.rs
@@ -118,6 +118,7 @@
                     reader: Box::new(include_bytes!("../tests/second.values").as_slice()),
                 },
             ],
+            crate::commands::DEFAULT_FLAG_PERMISSION,
         )
         .unwrap();
         crate::protos::parsed_flags::try_from_binary_proto(&bytes).unwrap()