Revert "[SPARK-17974] Refactor FileCatalog classes to simplify the inheritance tree"

sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala

...a/org/apache/spark/sql/execution/DataSourceScanExec.scala

...g/apache/spark/sql/execution/datasources/FileFormat.scala

...he/spark/sql/execution/datasources/HadoopFsRelation.scala

.../execution/datasources/PartitioningAwareFileCatalog.scala

...e/spark/sql/execution/datasources/PartitioningUtils.scala

.../spark/sql/execution/datasources/SessionFileCatalog.scala

...he/spark/sql/execution/datasources/TableFileCatalog.scala

...he/spark/sql/execution/datasources/FileCatalogSuite.scala

...k/sql/execution/datasources/SessionFileCatalogSuite.scala

.../datasources/parquet/ParquetPartitionDiscoverySuite.scala

...cala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala