Sort field push down

[penghuo]

New added features.

1. Add the fitler-sort push down optimizaiton rule in core engine. Rule: PushFilterUnderSort
   e.g. Filter - Sort - AnyChild will be optimized as Sort - Filter - AnyChild
2. Add the sort operator push down on Elasticseach storage engine. Rule: MergeSortAndIndexScan and MergeSortAndIndexRelation
   e.g. Sort - Relation will be optimized as IndexScan(sort)

Limitation

Currently, the storage engine layer optimzation depend on the Elasticsearch DSL to push down to sort expression. But there are some limitations of Elasticsearch DSL.

• Regardless the sort order (ASC/DESC), the doc has the field with NULL value always come before the doc missing the field.
• The script based sort can’t handle MISSING/NULL value
• The script based sort doesn’t support MISSING/NULL first/last paramater.

Thus, currently, the Sort Operator will push down to Elasticsearch query only when the sort by list include fields only. if the Sort operator include sort expression, the optimization will do nothing, it will still fall back to default memory based implementation.
e.g. source=index | sort abs(a) the expression abs(a) can't be push down to Elasticsearch DSL.

Changes

1. Remove the count from PPL sort command.
2. Remove the count from LogicalSort/PhysicalSort

Todo

1. Aggregation with Sort.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #848 (f537a5e) into develop (023f65a) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             develop     #848   +/-   ##
==========================================
  Coverage      99.85%   99.85%           
- Complexity      2102     2115   +13     
==========================================
  Files            209      214    +5     
  Lines           4678     4729   +51     
  Branches         308      308           
==========================================
+ Hits            4671     4722   +51     
  Misses             5        5           
  Partials           2        2           

Impacted Files	Coverage Δ	Complexity Δ
...endistroforelasticsearch/sql/executor/Explain.java	100.00% <ø> (ø)	27.00 <0.00> (ø)
...elasticsearch/sql/planner/logical/LogicalSort.java	100.00% <ø> (ø)	2.00 <0.00> (ø)
...ch/sql/planner/optimizer/LogicalPlanOptimizer.java	100.00% <ø> (ø)	7.00 <0.00> (ø)
...tor/protector/ElasticsearchExecutionProtector.java	100.00% <ø> (ø)	16.00 <0.00> (ø)
...ical/ElasticsearchLogicalPlanOptimizerFactory.java	100.00% <ø> (ø)	1.00 <0.00> (ø)
...arch/storage/script/filter/FilterQueryBuilder.java	100.00% <ø> (ø)	10.00 <0.00> (ø)
...troforelasticsearch/sql/ppl/parser/AstBuilder.java	100.00% <ø> (ø)	33.00 <0.00> (ø)
...orelasticsearch/sql/ppl/utils/ArgumentFactory.java	98.38% <ø> (-0.17%)	28.00 <0.00> (-4.00)
...orelasticsearch/sql/sql/parser/AstSortBuilder.java	100.00% <ø> (ø)	7.00 <0.00> (ø)
...ndistroforelasticsearch/sql/analysis/Analyzer.java	100.00% <100.00%> (ø)	43.00 <0.00> (ø)
... and 21 more

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[dai-chen]

LGTM. Thanks!