[SPARK-18038][SQL] Move output partitioning definition from UnaryNodeExec to its children

## What changes were proposed in this pull request?

Jira : https://issues.apache.org/jira/browse/SPARK-18038

This was a suggestion by rxin over one of the dev list discussion : http://apache-spark-developers-list.1001551.n3.nabble.com/Project-not-preserving-child-partitioning-td19417.html

His words:

>> It would be better (safer) to move the output partitioning definition into each of the operator and remove it from UnaryExecNode.

With this PR, following is the output partitioning and ordering for all the impls of `UnaryExecNode`.

UnaryExecNode's impl | outputPartitioning | outputOrdering | comment
------------ | ------------- | ------------ | ------------
AppendColumnsExec | child's | Nil | child's ordering can be used
AppendColumnsWithObjectExec | child's | Nil | child's ordering can be used
BroadcastExchangeExec | BroadcastPartitioning | Nil | -
CoalesceExec | UnknownPartitioning | Nil | -
CollectLimitExec | SinglePartition | Nil | -
DebugExec | child's | Nil | child's ordering can be used
DeserializeToObjectExec | child's | Nil | child's ordering can be used
ExpandExec | UnknownPartitioning | Nil | -
FilterExec | child's | child's | -
FlatMapGroupsInRExec | child's | Nil | child's ordering can be used
GenerateExec | child's | Nil | need to dig more
GlobalLimitExec | child's | child's | -
HashAggregateExec | child's | Nil | -
InputAdapter | child's | child's | -
InsertIntoHiveTable | child's | Nil | terminal node, doesn't need partitioning
LocalLimitExec | child's | child's | -
MapElementsExec | child's | child's | -
MapGroupsExec | child's | Nil | child's ordering can be used
MapPartitionsExec | child's | Nil | child's ordering can be used
ProjectExec | child's | child's | -
SampleExec | child's | Nil | child's ordering can be used
ScriptTransformation | child's | Nil | child's ordering can be used
SerializeFromObjectExec | child's | Nil | child's ordering can be used
ShuffleExchange | custom | Nil | -
SortAggregateExec | child's | sort over grouped exprs | -
SortExec | child's | custom | -
StateStoreRestoreExec  | child's | Nil | child's ordering can be used
StateStoreSaveExec | child's | Nil | child's ordering can be used
SubqueryExec | child's | child's | -
TakeOrderedAndProjectExec | SinglePartition | custom | -
WholeStageCodegenExec | child's | child's | -
WindowExec | child's | child's | -

## How was this patch tested?

This does NOT change any existing functionality so relying on existing tests

Author: Tejas Patil <tejasp@fb.com>

Closes #15575 from tejasapatil/SPARK-18038_UnaryNodeExec_output_partitioning.