Centralize token generation and formats

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135313726

javatests/google/registry/tools/CreateDomainCommandTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools;
 
 import com.beust.jcommander.ParameterException;
+import google.registry.testing.DeterministicStringGenerator;
 import org.junit.Before;
 import org.junit.Test;