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/HoodieReadClient.java

@@ -177,7 +177,7 @@ public class HoodieReadClient implements Serializable {
                             + hoodieTable.getMetaClient().getBasePath());
                 }
 
-                TableFileSystemView fileSystemView = new HoodieTableFileSystemView(hoodieTable.getMetaClient(),
+                TableFileSystemView.ReadOptimizedView fileSystemView = new HoodieTableFileSystemView(hoodieTable.getMetaClient(),
                         hoodieTable.getCompletedCommitTimeline(), fs.globStatus(new Path(path)));
                 List<HoodieDataFile> latestFiles = fileSystemView.getLatestDataFiles().collect(
                         Collectors.toList());