Add the ability to require premium fee acking for a registrar

When enabled for a registrar, all EPP operations on premium domains that have
costs (e.g.  creates, renews, transfers) will fail unless the EPP fee extension
is used to explicitly ack the amount of fee as part of the EPP transaction.

This ack is required regardless of whether premium fee acking is required at
the registry level. No data migration is necessary since false is the desired
default for this new attribute.

This CL also contains some slight refactoring of static utility methods used to
perform fee verification; there was short-circuiting at call-sites in two
places when what was really needed was two methods, one implementing additional
functionality on top of the other, and calling the inner method in the places
where short-circuiting had previously been necessary.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=184229363

java/google/registry/model/registrar/Registrar.java

@@ -412,6 +412,13 @@ public class Registrar extends ImmutableObject implements Buildable, Jsonifiable
    */
   BillingMethod billingMethod;
 
+  /** Whether the registrar must acknowledge the price to register non-standard-priced domains. */
+  boolean premiumPriceAckRequired;
+
+  public boolean getPremiumPriceAckRequired() {
+    return premiumPriceAckRequired;
+  }
+
   @NonFinalForTesting
   private static Supplier<byte[]> saltSupplier =
       () -> {
@@ -864,6 +871,11 @@ public class Registrar extends ImmutableObject implements Buildable, Jsonifiable
       return this;
     }
 
+    public Builder setPremiumPriceAckRequired(boolean premiumPriceAckRequired) {
+      getInstance().premiumPriceAckRequired = premiumPriceAckRequired;
+      return this;
+    }
+
     /** Build the registrar, nullifying empty fields. */
     @Override
     public Registrar build() {

java/google/registry/model/registry/Registry.java

@@ -318,7 +318,7 @@ public class Registry extends ImmutableObject implements Buildable {
   /** Whether the pull queue that writes to authoritative DNS is paused for this TLD. */
   boolean dnsPaused = DEFAULT_DNS_PAUSED;
 
-  /** Whether the price must be acknowledged to register premiun names on this TLD. */
+  /** Whether the price must be acknowledged to register premium names on this TLD. */
   boolean premiumPriceAckRequired = true;
 
   /**