Support remote directories in authfs_service

Also take advantage of the new nested type in AIDL.

Bug: 205750213
Test: Can use the API locally
Change-Id: I8f7e63dedeb6dd72433f70807dcc65288c702097
diff --git a/authfs/src/main.rs b/authfs/src/main.rs
index 24b041c..f0c94c5 100644
--- a/authfs/src/main.rs
+++ b/authfs/src/main.rs
@@ -129,7 +129,7 @@
     /// A mapping file that describes the expecting file/directory structure and integrity metadata
     /// in the remote directory. The file contains serialized protobuf of
     /// android.security.fsverity.FSVerityDigests.
-    /// TODO(203251769): Really use the file when it's generated.
+    /// TODO(206869687): Really use the file when it's generated.
     #[allow(dead_code)]
     mapping_file_path: PathBuf,
 
@@ -252,7 +252,7 @@
             AuthFsEntry::ReadonlyDirectory { dir: InMemoryDir::new() },
         )?;
 
-        // TODO(203251769): Read actual path from config.mapping_file_path when it's generated.
+        // TODO(206869687): Read actual path from config.mapping_file_path when it's generated.
         let paths = vec![
             Path::new("/system/framework/framework.jar"),
             Path::new("/system/framework/services.jar"),
@@ -268,7 +268,7 @@
                     related_path,
                 )?;
                 let file_size = service.getFileSize(remote_file.get_remote_fd())?.try_into()?;
-                // TODO(203251769): Switch to VerifiedReadonly
+                // TODO(206869687): Switch to VerifiedReadonly
                 AuthFsEntry::UnverifiedReadonly { reader: remote_file, file_size }
             };
             authfs.add_entry_at_ro_dir_by_path(