Simplify the Ghostryde API

First step of RDE encoding refactoring.

Creates a single InputStream (OutputStream) to decode (encode) Ghostryde files.
This replaces the 3 InputStreams (OutputStreams) that were needed before.

Also removes a lot of classes, and removes the "injection" of the Ghostryde
class. It's an encoding, there's no point in injecting it.

Finally, removed the buffer-size configuration and replaced with a static final
const value. It's just a buffer size - it doesn't actually affect much. There
are much more "important" fields that weren't configured (such as the
compression algorithm and whether or not to do integrity checks)

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=202319102

java/google/registry/tools/ValidateEscrowDepositCommand.java

@@ -65,13 +65,10 @@ final class ValidateEscrowDepositCommand implements Command {
   @Override
   public void run() throws Exception {
     if (input.toString().endsWith(".ghostryde")) {
-      Ghostryde ghostryde = new Ghostryde(64 * 1024);
       try (InputStream in = Files.newInputStream(input);
-          Ghostryde.Decryptor decryptor =
-              ghostryde.openDecryptor(in, keyring.getRdeStagingDecryptionKey());
-          Ghostryde.Decompressor decompressor = ghostryde.openDecompressor(decryptor);
-          Ghostryde.Input ghostInput = ghostryde.openInput(decompressor)) {
-        validateXmlStream(ghostInput);
+          InputStream ghostrydeDecoder =
+              Ghostryde.decoder(in, keyring.getRdeStagingDecryptionKey())) {
+        validateXmlStream(ghostrydeDecoder);
       }
     } else {
       try (InputStream inputStream = Files.newInputStream(input)) {