Implement "premium price ack required" checkbox

Implement a checkbox in the "Resources" tab to allow registrars to toggle
their "premium price ack required" flag.

Tested:
  Verfied the console functionality by hand.  I've started work on an
  automated test, but we can't actually test those from blaze and the
  kokoro tests are way too time-consuming to be practical for development, so
  we're going to have to either find a way to run those locally outside of
  the normal process or make do without a test.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190212177

java/google/registry/ui/externs/json.js

@@ -84,7 +84,8 @@ registry.json.Response.prototype.results;
  *   localizedAddress: registry.json.RegistrarAddress,
  *   whoisServer: (string?|undefined),
  *   referralUrl: (string?|undefined),
- *   contacts: !Array.<registry.json.RegistrarContact>
+ *   contacts: !Array.<registry.json.RegistrarContact>,
+ *   premiumPriceAckRequired: boolean
  * }}
  */
 registry.json.Registrar;