Add Google Analytics to registrar console

To support the open source community, which may want to use different analytics services, we implement a soy template for analytics services that:

1) Does not require users to implement Google Analytics
2) Allows users to add their own analytics code to `Analytics.soy`
3) Gives users the flexibility to pass as much or as little static configuration to their custom analytics code as needed.
4) Ensures that users can merge upstream Nomulus code in the future without having to delete their custom analytics implementations
5) Does not allow code to be injected from configuration, which Soy as a framework actively discourages.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=248340081

java/google/registry/config/files/default-config.yaml

@@ -332,6 +332,11 @@ registrarConsole:
   # URL linking to directory of technical support docs on the registry.
   technicalDocsUrl: http://example.com/your_support_docs/
 
+  # Configuration for all analytics services installed in the web console
+  analyticsConfig:
+    # Google Analytics account where data on console use is sent, optional
+    googleAnalyticsId: null
+
 monitoring:
   # Max queries per second for the Google Cloud Monitoring V3 (aka Stackdriver)
   # API. The limit can be adjusted by contacting Cloud Support.