Add sharded DNS publishing capability

This enables sharded DNS publishing on a per-TLD basis. Instead of a TLD-wide lock, the sharded scheme locks each update on the shard number, allowing parallel writes to DNS.

We allow N (the number of shards) to be 0 or 1 for no sharding, and N > 1 for an N-way sharding scheme. Unless explicitly set, all TLDs default to a numShards of 0, so we don't have to reload all registry objects explicitly.

WARNING: This will change the lock name upon deployment for the PublishDnsAction from "<TLD> Dns Updates" to "<TLD> Dns Updates shard 0". This may cause concurrency issues if the underlying DNSWriter is not parallel-write tolerant (currently all production usages are ZonemanWriter, which is parallel-tolerant, so no issues are expected).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=187525655

java/google/registry/tools/CreateOrUpdateTldCommand.java

@@ -232,6 +232,16 @@ abstract class CreateOrUpdateTldCommand extends MutatingCommand {
     description = "A comma-separated list of DnsWriter implementations to use")
   List<String> dnsWriters;
 
+  @Nullable
+  @Parameter(
+    names = {"--num_dns_publish_locks"},
+    description =
+        "The number of publish locks we allow in parallel for DNS updates under this tld "
+            + "(1 for TLD-wide locks)",
+    arity = 1
+  )
+  Integer numDnsPublishShards;
+
   @Nullable
   @Parameter(
       names = "--lrp_period",
@@ -347,6 +357,7 @@ abstract class CreateOrUpdateTldCommand extends MutatingCommand {
       Optional.ofNullable(lordnUsername).ifPresent(u -> builder.setLordnUsername(u.orElse(null)));
       Optional.ofNullable(claimsPeriodEnd).ifPresent(builder::setClaimsPeriodEnd);
       Optional.ofNullable(domainCreateRestricted).ifPresent(builder::setDomainCreateRestricted);
+      Optional.ofNullable(numDnsPublishShards).ifPresent(builder::setNumDnsPublishLocks);
       Optional.ofNullable(lrpPeriod).ifPresent(p -> builder.setLrpPeriod(p.orElse(null)));
 
       if (premiumListName != null) {
@@ -410,7 +421,7 @@ abstract class CreateOrUpdateTldCommand extends MutatingCommand {
           Joiner.on(", ").join(invalidNames),
           tld);
       if (overrideReservedListRules) {
-        System.err.println("Error overriden: " + errMsg);
+        System.err.println("Error overridden: " + errMsg);
       } else {
         throw new IllegalArgumentException(errMsg);
       }