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.

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

java/google/registry/ui/server/registrar/RegistrarSettingsAction.java

@@ -67,8 +67,8 @@ public class RegistrarSettingsAction implements Runnable, JsonActionRunner.JsonA
 
   public static final String PATH = "/registrar-settings";
 
-  private static final String OP_PARAM = "op";
-  private static final String ARGS_PARAM = "args";
+  static final String OP_PARAM = "op";
+  static final String ARGS_PARAM = "args";
 
   @Inject HttpServletRequest request;
   @Inject JsonActionRunner jsonActionRunner;
@@ -93,7 +93,7 @@ public class RegistrarSettingsAction implements Runnable, JsonActionRunner.JsonA
       throw new BadRequestException("Malformed JSON");
     }
 
-    Registrar initialRegistrar = sessionUtils.getRegistrarForAuthResult(request, authResult);
+    Registrar initialRegistrar = sessionUtils.getRegistrarForAuthResult(request, authResult, false);
     // Process the operation.  Though originally derived from a CRUD
     // handler, registrar-settings really only supports read and update.
     String op = Optional.ofNullable((String) input.get(OP_PARAM)).orElse("read");