Add tests for LabelNormalizer

These use the full InMemoryModule stack because depending on users,
groups, label types, and permissions is heavyweight.

The careful reader will notice based on the tested behavior that there
are still some outstanding bugs in label normalization during submit
time. For example, since Submit only upserts the normalized list of
approvals, any labels omitted by the normalizer due to an empty
permission range are left entirely untouched. Such bugs are not fixed
by this change, which is only to add tests.

Change-Id: I955ee8c63b17812684f8350113cb0f2f1bf72fe6

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/PatchSetApproval.java

@@ -19,6 +19,7 @@ import com.google.gwtorm.client.CompoundKey;
 import com.google.gwtorm.client.StringKey;
 
 import java.sql.Timestamp;
+import java.util.Objects;
 
 /** An approval (or negative approval) on a patch set. */
 public final class PatchSetApproval {
@@ -190,4 +191,20 @@ public final class PatchSetApproval {
     return new StringBuilder().append('[').append(key).append(": ")
         .append(value).append(']').toString();
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (o instanceof PatchSetApproval) {
+      PatchSetApproval p = (PatchSetApproval) o;
+      return Objects.equals(key, p.key)
+          && Objects.equals(value, p.value)
+          && Objects.equals(granted, p.granted);
+    }
+    return false;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(key, value, granted);
+  }
 }