[Backport 2.x] Allow common keywords and scalar function name used as identifier

[opensearch-trigger-bot]

Backport 2f4924a from #1191

[codecov-commenter]

Codecov Report

Merging #1212 (2f4924a) into 2.x (16606e4) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 2f4924a differs from pull request most recent head fdae569. Consider uploading reports for the commit fdae569 to get more accurate results

@@             Coverage Diff              @@
##                2.x    #1212      +/-   ##
============================================
- Coverage     98.32%   98.32%   -0.01%     
+ Complexity     3553     3548       -5     
============================================
  Files           346      344       -2     
  Lines          8761     8753       -8     
  Branches        555      554       -1     
============================================
- Hits           8614     8606       -8     
  Misses          142      142              
  Partials          5        5              

Flag	Coverage Δ
sql-engine	98.32% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...expression/function/RelevanceFunctionResolver.java	100.00% <ø> (ø)
...ch/sql/planner/optimizer/LogicalPlanOptimizer.java	100.00% <ø> (ø)
...rg/opensearch/sql/analysis/ExpressionAnalyzer.java	100.00% <100.00%> (ø)
...c/main/java/org/opensearch/sql/expression/DSL.java	100.00% <100.00%> (ø)
...arch/sql/expression/datetime/DateTimeFunction.java	100.00% <100.00%> (ø)
...h/sql/expression/function/BuiltinFunctionName.java	100.00% <100.00%> (ø)
...h/sql/expression/function/OpenSearchFunctions.java	100.00% <100.00%> (ø)
...org/opensearch/sql/planner/DefaultImplementor.java	100.00% <100.00%> (ø)
...opensearch/sql/planner/logical/LogicalPlanDSL.java	100.00% <100.00%> (ø)
...ch/sql/planner/logical/LogicalPlanNodeVisitor.java	100.00% <100.00%> (ø)
... and 25 more

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