[HUDI-1681] Support object storage for Flink writer (#2662)

In order to support object storage, we need these changes:

* Use the Hadoop filesystem so that we can find the plugin filesystem
* Do not fetch file size until the file handle is closed
* Do not close the opened filesystem because we want to use the
  filesystem cache

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/HoodieAppendHandle.java

@@ -274,6 +274,7 @@ public class HoodieAppendHandle<T extends HoodieRecordPayload, I, K, O> extends
     if (!stat.getLogFiles().contains(result.logFile().getFileName())) {
       stat.addLogFiles(result.logFile().getFileName());
     }
+    stat.setFileSizeInBytes(result.size());
   }
 
   private void updateRuntimeStats(HoodieDeltaWriteStat stat) {
@@ -304,6 +305,7 @@ public class HoodieAppendHandle<T extends HoodieRecordPayload, I, K, O> extends
     } else if (stat.getPath().endsWith(result.logFile().getFileName())) {
       // append/continued writing to the same log file
       stat.setLogOffset(Math.min(stat.getLogOffset(), result.offset()));
+      stat.setFileSizeInBytes(stat.getFileSizeInBytes() + result.size());
       accumulateWriteCounts(stat, result);
       accumulateRuntimeStats(stat);
     } else {

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/storage/HoodieFileWriter.java

@@ -33,4 +33,6 @@ public interface HoodieFileWriter<R extends IndexedRecord> {
   void close() throws IOException;
 
   void writeAvro(String key, R oldRecord) throws IOException;
+
+  long getBytesWritten();
 }

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/storage/HoodieHFileWriter.java

@@ -156,4 +156,9 @@ public class HoodieHFileWriter<T extends HoodieRecordPayload, R extends IndexedR
     writer.close();
     writer = null;
   }
+
+  @Override
+  public long getBytesWritten() {
+    return fs.getBytesWritten(file);
+  }
 }

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/storage/HoodieParquetWriter.java

@@ -94,4 +94,9 @@ public class HoodieParquetWriter<T extends HoodieRecordPayload, R extends Indexe
     super.write(object);
     writeSupport.add(key);
   }
+
+  @Override
+  public long getBytesWritten() {
+    return fs.getBytesWritten(file);
+  }
 }