Introduce ReadOptimizedView & RealtimeView out of TableFileSystemView

- Usage now marks code as clearly using either RO or RT views, for future evolution
  - Tests on all of FileGroups and FileSlices

hoodie-client/src/main/java/com/uber/hoodie/table/HoodieCopyOnWriteTable.java

@@ -311,7 +311,7 @@ public class HoodieCopyOnWriteTable<T extends HoodieRecordPayload> extends Hoodi
 
             if (!commitTimeline.empty()) { // if we have some commits
                 HoodieInstant latestCommitTime = commitTimeline.lastInstant().get();
-                List<HoodieDataFile> allFiles = getFileSystemView()
+                List<HoodieDataFile> allFiles = getROFileSystemView()
                     .getLatestDataFilesBeforeOrOn(partitionPath, latestCommitTime.getTimestamp())
                     .collect(Collectors.toList());
 

hoodie-client/src/main/java/com/uber/hoodie/table/HoodieTable.java

@@ -108,6 +108,24 @@ public abstract class HoodieTable<T extends HoodieRecordPayload> implements Seri
         return new HoodieTableFileSystemView(metaClient, getCompletedCommitTimeline());
     }
 
+    /**
+     * Get the read optimized view of the file system for this table
+     *
+     * @return
+     */
+    public TableFileSystemView.ReadOptimizedView getROFileSystemView() {
+        return new HoodieTableFileSystemView(metaClient, getCompletedCommitTimeline());
+    }
+
+    /**
+     * Get the real time view of the file system for this table
+     *
+     * @return
+     */
+    public TableFileSystemView.RealtimeView getRTFileSystemView() {
+        return new HoodieTableFileSystemView(metaClient, getCompletedCommitTimeline());
+    }
+
     /**
      * Get the view of the file system for this table
      *