GCS client library migration in Java SDK - part 1 (#36876)

* Make a copy of GcsUtil.java as GcsUtilLegacy.java

* Change references from GcsUtil to GcsUtilLegacy in GcsUtilLegacy.java

* Change public apis in GcsUtil.java to call the GcsUtilLegacy.java

* Add mocking GcsUtilLegacy for tests and remove unnecessary references of gcsio in GcsUtil

* Possible breaking change: removed unused public functions.

* Get rid of the last bit (read option) gcsio references in GcsUtil.java.

* Route the code path of open reading files to include api count metric.

* Spotless check

* Remove BatchInterface and RewriteOp from GcsUtil.java. Simplify some functions.

* Rename GcsUtilLegacy to GcsUtilV1

* Make GcsUtilV1 package private

* Import ExperimentalOptions

* Move GcsReadOptionsFactory from GcsUtilV1 to GcsOptions

* Fix a failed test

* Add comments to SupressWarnings

* Fix test

Author: shunping

sdks/java/extensions/google-cloud-platform-core/src/main/java/org/apache/beam/sdk/extensions/gcp/options/GcsOptions.java

@@ -46,13 +46,24 @@ public interface GcsOptions extends ApplicationNameOptions, GcpOptions, Pipeline
 
   void setGcsUtil(GcsUtil value);
 
+  class GcsReadOptionsFactory implements DefaultValueFactory<GoogleCloudStorageReadOptions> {
+    @Override
+    public GoogleCloudStorageReadOptions create(PipelineOptions options) {
+      return GoogleCloudStorageReadOptions.DEFAULT;
+    }
+  }
+
+  /** @deprecated This option will be removed in a future release. */
   @JsonIgnore
   @Description(
       "The GoogleCloudStorageReadOptions instance that should be used to read from Google Cloud Storage.")
-  @Default.InstanceFactory(GcsUtil.GcsReadOptionsFactory.class)
+  @Default.InstanceFactory(GcsReadOptionsFactory.class)
   @Hidden
+  @Deprecated
   GoogleCloudStorageReadOptions getGoogleCloudStorageReadOptions();
 
+  /** @deprecated This option will be removed in a future release. */
+  @Deprecated
   void setGoogleCloudStorageReadOptions(GoogleCloudStorageReadOptions value);
 
   /**