Make FlowReporter log tld and various other fields

As part of b/36599833, this makes FlowReporter log the tld(s) of every domain
flow it executes, so we can provide ICANN reporting totals on a per-TLD basis.

It also adds several other fields that we're computing anyway and which seem
useful, particularly for debugging any issues we see in production with the data
that we're attempting to record for ICANN reporting.  The full set of fields is:

  - commandType (e.g. "create", "info", "transfer")
  - resourceType* (e.g. "domain", "contact", "host")
  - flowClassName (e.g. "ContactCreateFlow", "DomainRestoreRequestFlow")
  - targetId* (e.g. "ns1.foo.com", "bar.org", "contact-1234")
  - targetIds* - plural of the above, for multi-resource checks
  - tld** (e.g. "com", "co.uk") - extracted from targetId, lowercased
  - tlds** - plural of the above, deduplicated, for multi-resource checks

* = only non-empty for resource flows (not e.g. login, logout, poll)
** = only non-empty for domain flows

Note that TLD extraction is deliberately very lenient to avoid the complexity
overhead of double-validation of the domain names in the common case.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154070794

javatests/google/registry/flows/domain/DomainApplicationCreateFlowTest.java

@@ -1812,5 +1812,8 @@ public class DomainApplicationCreateFlowTest
     clock.advanceOneMilli();
     runFlow();
     assertIcannReportingActivityFieldLogged("srs-dom-create");
+    assertTldsFieldLogged("tld");
+    // Ensure we log the client ID for srs-dom-create so we can also use it for attempted-adds.
+    assertClientIdFieldLogged("TheRegistrar");
   }
 }