Refactor StringGenerator bindings

Make every dependency request explicit on what encoding is used. Also get rid of InjectRule in XjcToDomainResourceConverterTest.

Random number generator providers are separated to secure and insecure ones. The insecure ones must be explicitly requested (usually for use cases where security is not of concern, for better speed).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=217921422

java/google/registry/tools/CreateDomainCommand.java

@@ -23,6 +23,7 @@ import static org.joda.time.DateTimeZone.UTC;
 import com.beust.jcommander.Parameter;
 import com.beust.jcommander.Parameters;
 import com.google.template.soy.data.SoyMapData;
+import google.registry.config.RegistryConfig.Config;
 import google.registry.model.pricing.PremiumPricingEngine.DomainPrices;
 import google.registry.tools.soy.DomainCreateSoyInfo;
 import google.registry.util.StringGenerator;
@@ -46,6 +47,7 @@ final class CreateDomainCommand extends CreateOrUpdateDomainCommand
   private boolean forcePremiums;
 
   @Inject
+  @Config("base64StringGenerator")
   StringGenerator passwordGenerator;
 
   private static final int PASSWORD_LENGTH = 16;