[SPARK-17974] try 2) Refactor FileCatalog classes to simplify the inheritance tree

## What changes were proposed in this pull request?

This renames `BasicFileCatalog => FileCatalog`, combines  `SessionFileCatalog` with `PartitioningAwareFileCatalog`, and removes the old `FileCatalog` trait.

In summary,
```
MetadataLogFileCatalog extends PartitioningAwareFileCatalog
ListingFileCatalog extends PartitioningAwareFileCatalog
PartitioningAwareFileCatalog extends FileCatalog
TableFileCatalog extends FileCatalog
```

(note that this is a re-submission of https://github.com/apache/spark/pull/15518 which got reverted)

## How was this patch tested?

Existing tests

Author: Eric Liang <ekl@databricks.com>

Closes #15533 from ericl/fix-scalastyle-revert.