Project operator pushdown

[penghuo]

Issue #, if available: N/A

Description of changes:

1. Add Project push down in Elasticsearch storage engine layer.
2. Doc. https://github.com/penghuo/sql/blob/project-pushdown/docs/user/optimization/optimization.rst#push-project-into-query-dsl

*Todo: #934

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 #933 (faeb36f) into develop (64c7bd6) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##             develop     #933    +/-   ##
===========================================
  Coverage      99.86%   99.87%            
- Complexity      2265     2340    +75     
===========================================
  Files            229      232     +3     
  Lines           5235     5389   +154     
  Branches         346      350     +4     
===========================================
+ Hits            5228     5382   +154     
  Misses             5        5            
  Partials           2        2            

Impacted Files	Coverage Δ	Complexity Δ
...ical/ElasticsearchLogicalPlanOptimizerFactory.java	100.00% <ø> (ø)	1.00 <0.00> (ø)
...icsearch/sql/expression/ExpressionNodeVisitor.java	100.00% <100.00%> (ø)	14.00 <1.00> (ø)
...planner/logical/ElasticsearchLogicalIndexScan.java	100.00% <100.00%> (ø)	7.00 <3.00> (+3.00)
...ch/planner/logical/rule/OptimizationRuleUtils.java	100.00% <100.00%> (ø)	9.00 <3.00> (+3.00)
.../planner/logical/rule/PushProjectAndIndexScan.java	100.00% <100.00%> (ø)	7.00 <7.00> (?)
...h/planner/logical/rule/PushProjectAndRelation.java	100.00% <100.00%> (ø)	5.00 <5.00> (?)
.../sql/elasticsearch/storage/ElasticsearchIndex.java	100.00% <100.00%> (ø)	3.00 <0.00> (ø)
.../elasticsearch/storage/ElasticsearchIndexScan.java	100.00% <100.00%> (ø)	19.00 <1.00> (+1.00)
...opendistroforelasticsearch/sql/expression/DSL.java	100.00% <0.00%> (ø)	128.00% <0.00%> (+9.00%)
...elasticsearch/sql/analysis/ExpressionAnalyzer.java	100.00% <0.00%> (ø)	31.00% <0.00%> (+1.00%)
... and 6 more

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[dai-chen]

Thanks for the changes!