Isolate customizable code in activity reporting

Modularize the code for DNS count reporting to allow it to be customized for
more flexible systems.
Tested:
  Uploaded to alpha with hacks to allow admin initiating and logging from the
  DnsCountQueryCoordinatorModule, verified that the provider function is invoked and
  that the action runs successfully.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=225225587

java/google/registry/config/RegistryConfig.java

@@ -1135,6 +1135,12 @@ public final class RegistryConfig {
       return config.registryPolicy.allocationTokenCustomLogicClass;
     }
 
+    @Provides
+    @Config("dnsCountQueryCoordinatorClass")
+    public static String dnsCountQueryCoordinatorClass(RegistryConfigSettings config) {
+      return config.registryPolicy.dnsCountQueryCoordinatorClass;
+    }
+
     /** Returns the disclaimer text for the exported premium terms. */
     @Provides
     @Config("premiumTermsExportDisclaimer")