Import upstream v0.16.23, stripped

Upstream commit: 9d1c75ab68435e4417337f768291e5f947686203
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 118 in 50 files
Dangling module declarations removed: 5
Edits turning enterprise off: 25
Third-party code: 14 files, 0 not in THIRD-PARTY.md
Verification: clean

One snippet more than v0.16.22, in crates/common/src/auth/authentication.rs
(3, was 2).

tests/src/smtp/outbound/fallback_relay.rs

@@ -127,7 +127,9 @@ async fn fallback_relay() {
     let next_due = now();
     let queue_id = retry.queue_id;
     retry.message.recipients[0].retry.due = next_due;
-    retry.save_changes(&local.server, prev_due.into()).await;
+    retry
+        .save_changes(&local.server, prev_due.into(), None)
+        .await;
     local
         .delivery_attempt(queue_id)
         .await

tests/src/smtp/outbound/tls.rs

@@ -144,7 +144,9 @@ async fn starttls_optional() {
     let next_due = now();
     let queue_id = retry.queue_id;
     retry.message.recipients[0].retry.due = next_due;
-    retry.save_changes(&local.server, prev_due.into()).await;
+    retry
+        .save_changes(&local.server, prev_due.into(), None)
+        .await;
     local
         .delivery_attempt_for_queue(queue_id, "default")
         .await