Add TLDs parameter to refresh DNS action

This will allow us to migrate one TLD at a time by refreshing all zones
on the specified TLD after dual-writing is enabled.

Note that the TLDs parameter is required, which seems reasonable given
that almost all imagined use cases would be on a by-TLD basis.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=160294546

javatests/google/registry/tools/server/BUILD

@@ -12,6 +12,7 @@ java_library(
     srcs = glob(["*.java"]),
     resources = glob(["testdata/*"]),
     deps = [
+        "//java/google/registry/dns",
         "//java/google/registry/groups",
         "//java/google/registry/mapreduce",
         "//java/google/registry/model",