mononoke: populate pusher_identities in GitRefLogger

Summary:
The git_ref scuba table was logging empty pusher_identities for every git ref update because `GitBookmarkInfo::log_to_logger` hardcoded `vec![]`. The original comment said this was "Maintaining parity with current Git logger", but having no pusher attribution makes it impossible to investigate who is pushing what to git refs.

Capture the identities from `ctx.metadata().identities()` at `GitBookmarkInfo` construction time, mirroring how `PlainCommitInfo` populates `user_identities` in `commit_logger.rs`.

Reviewed By: YousefSalama

Differential Revision: D104252354

fbshipit-source-id: 626c4f19c8ae78520e4c3b258e84b175ab9e9406

Author: mzr

eden/mononoke/features/repo_update_logger/src/bookmark_logger.rs

@@ -106,6 +106,7 @@ struct GitBookmarkInfo {
     bookmark_name: String,
     old_bookmark_value: String,
     new_bookmark_value: String,
+    pusher_identities: Vec<String>,
     server_hostname: String,
     timestamp: u128,
 }
@@ -129,12 +130,19 @@ impl GitBookmarkInfo {
         let new_bookmark_value = get_git_hash(ctx, repo, info.operation.new_bookmark_value())
             .await
             .unwrap_or_else(|| ObjectId::null(Kind::Sha1).to_hex().to_string());
+        let pusher_identities = ctx
+            .metadata()
+            .identities()
+            .iter()
+            .map(|i| i.to_typed_string())
+            .collect();
         let server_hostname = get_hostname().unwrap_or("error".to_string());
         Self {
             repo_name,
             bookmark_name,
             old_bookmark_value,
             new_bookmark_value,
+            pusher_identities,
             server_hostname,
             timestamp,
         }
@@ -157,7 +165,7 @@ impl Loggable for GitBookmarkInfo {
         ref_logger.set_ref_name(self.bookmark_name.clone());
         ref_logger.set_old_ref_value(self.old_bookmark_value.clone());
         ref_logger.set_new_ref_value(self.new_bookmark_value.clone());
-        ref_logger.set_pusher_identities(vec![]); // Maintaining parity with current Git logger
+        ref_logger.set_pusher_identities(self.pusher_identities.clone());
         ref_logger.set_server_hostname(self.server_hostname.clone());
         ref_logger.set_received_timestamp(self.timestamp as i64);
         if let Some(cri) = ctx.client_request_info() {