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

javatests/google/registry/ui/js/registrar/console_test.js

@@ -128,11 +128,13 @@ function testNavToResources() {
   registry.registrar.ConsoleTestUtil.visit(test, {
     path: 'resources',
     xsrfToken: test.testXsrfToken,
-    technicalDocsUrl: 'http://example.com/techdocs'
+    technicalDocsUrl: 'http://example.com/techdocs',
+    premiumPriceAckRequired: false,
+    readonly: true,
   });
   var xhr = goog.testing.net.XhrIo.getSendInstances().pop();
   assertTrue(xhr.isActive());
-  assertEquals('/registrar-settings', xhr.getLastUri());
+  assertEquals('/registrar-premium-price-ack', xhr.getLastUri());
   assertEquals(test.testXsrfToken,
                xhr.getLastRequestHeaders().get('X-CSRF-Token'));
   xhr.simulateResponse(200, goog.json.serialize({