Allow choice of Keyring to be configured in YAML

This uses a Dagger-provided map of Keyring implementations, with two currently available,
"KMS" and "Dummy". The active keyring is configured in the YAML file, so we no longer
require MOE directives to choose which one to use for internal/external builds.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=216898058

java/google/registry/tools/RegistryToolComponent.java

@@ -21,6 +21,8 @@ import google.registry.config.RegistryConfig.ConfigModule;
 import google.registry.dns.writer.VoidDnsWriterModule;
 import google.registry.dns.writer.clouddns.CloudDnsWriterModule;
 import google.registry.dns.writer.dnsupdate.DnsUpdateWriterModule;
+import google.registry.keyring.KeyringModule;
+import google.registry.keyring.api.DummyKeyringModule;
 import google.registry.keyring.api.KeyModule;
 import google.registry.keyring.kms.KmsModule;
 import google.registry.rde.RdeModule;
@@ -52,13 +54,14 @@ import javax.inject.Singleton;
       ConfigModule.class,
       CredentialModule.class,
       DatastoreServiceModule.class,
-      google.registry.keyring.api.DummyKeyringModule.class,
+      DummyKeyringModule.class,
       CloudDnsWriterModule.class,
       DefaultRequestFactoryModule.class,
       DefaultRequestFactoryModule.RequestFactoryModule.class,
       DnsUpdateWriterModule.class,
       Jackson2Module.class,
       KeyModule.class,
+      KeyringModule.class,
       KmsModule.class,
       RdeModule.class,
       RegistryToolModule.class,