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/tmch/NordnUploadAction.java

@@ -89,7 +89,7 @@ public final class NordnUploadAction implements Runnable {
 
   @Inject Clock clock;
   @Inject Retrier retrier;
-  @Inject Random random;
+  @Inject @Config("insecureRandom") Random random;
   @Inject LordnRequestInitializer lordnRequestInitializer;
   @Inject URLFetchService fetchService;
   @Inject @Config("tmchMarksdbUrl") String tmchMarksdbUrl;