DRILL-6381: (Part 1) Secondary Index framework
1. Secondary Index planning interfaces and abstract classes like DBGroupScan, DbSubScan, IndexDecriptor etc.
2. Statistics and Cost model interfaces/classes: PluginCost, Statistics, StatisticsPayload, AbstractIndexStatistics
3. ScanBatch and RecordReader to support repeatable scan
4. Secondary Index execution related interfaces: RangePartitionSender, RowKeyJoin, PartitionFunction
5. MD-3979: Query using cast index plan fails with NPE
Co-authored-by: Aman Sinha <asinha@maprtech.com>
Co-authored-by: chunhui-shi <cshi@maprtech.com>
Co-authored-by: Gautam Parai <gparai@maprtech.com>
Co-authored-by: Padma Penumarthy <ppenumar97@yahoo.com>
Co-authored-by: Hanumath Rao Maduri <hmaduri@maprtech.com>
Conflicts:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/ScanBatch.java
exec/java-exec/src/main/java/org/apache/drill/exec/planner/common/DrillRelOptUtil.java
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillTable.java
protocol/src/main/java/org/apache/drill/exec/proto/UserBitShared.java
protocol/src/main/java/org/apache/drill/exec/proto/beans/CoreOperatorType.java
protocol/src/main/protobuf/UserBitShared.proto
