Copy labels dynamically in ApprovalsUtil.byPatchSet

The intent is to use this method from ChangeJson to dynamically copy
labels every time the change detail is loaded, thus not relying on
one-time copying of labels in the notedb read path.

To do so requires a bit of refactoring, since the ChangeControl now
needs to be passed into this method.

Change-Id: I8bc25d32a91218e074517dcacf4bf3a77d4ae957

gerrit-server/src/main/java/com/google/gerrit/server/ApprovalCopier.java

@@ -81,6 +81,11 @@ public class ApprovalCopier {
     db.patchSetApprovals().insert(getForPatchSet(db, ctl, ps));
   }
 
+  Iterable<PatchSetApproval> getForPatchSet(ReviewDb db,
+      ChangeControl ctl, PatchSet.Id psId) throws OrmException {
+    return getForPatchSet(db, ctl, db.patchSets().get(psId));
+  }
+
   private Iterable<PatchSetApproval> getForPatchSet(ReviewDb db,
       ChangeControl ctl, PatchSet ps) throws OrmException {
     ChangeData cd = changeDataFactory.create(db, ctl);