DRILL-6331: Revisit Hive Drill native parquet implementation to be exposed to Drill optimizations (filter / limit push down, count to direct scan)
1. Factored out common logic for Drill parquet reader and Hive Drill native parquet readers: AbstractParquetGroupScan, AbstractParquetRowGroupScan, AbstractParquetScanBatchCreator.
2. Rules that worked previously only with ParquetGroupScan, now can be applied for any class that extends AbstractParquetGroupScan: DrillFilterItemStarReWriterRule, ParquetPruneScanRule, PruneScanRule.
3. Hive populated partition values based on information returned from Hive metastore. Drill populates partition values based on path difference between selection root and actual file path.
Before ColumnExplorer populated partition values based on Drill approach. Since now ColumnExplorer populates values for parquet files from Hive tables,
`populateImplicitColumns` method logic was changed to populated partition columns only based on given partition values.
4. Refactored ParquetPartitionDescriptor to be responsible for populating partition values rather than storing this logic in parquet group scan class.
5. Metadata class was moved to separate metadata package (org.apache.drill.exec.store.parquet.metadata). Factored out several inner classed to improve code readability.
6. Collected all Drill native parquet reader unit tests into one class TestHiveDrillNativeParquetReader, also added new tests to cover new functionality.
7. Reduced excessive logging when parquet files metadata is read
closes #1214
