Add support for metadata fields (_id) to be used as QualifiedName

[acarbonetto]

Description

OpenSearch reserved fields (_id, _score, _index, etc) are not allowed to be used in SQL clauses (SELECT, WHERE, ORDER BY) because the field format starting with underscore _ is not allowed.

This ticket adds specific identifiers to the language, and opens up support for OpenSearch reserved identifiers.

As an aside, identifiers with double underscore at the start (such as __myCoolField) is acceptable as a indentifier.

Example:
SELECT calcs.key, str0, _id, _score, _maxscore FROM calcs WHERE _id="5"

Result:
{ "key04", "OFFICE SUPPLIES", "5", null, null }

Issues Resolved

#639

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Merging #141 (c13c5fa) into integ-poc-metadata-fields (bfad32c) will decrease coverage by 35.19%.
The diff coverage is n/a.

@@                       Coverage Diff                        @@
##             integ-poc-metadata-fields     #141       +/-   ##
================================================================
- Coverage                        97.95%   62.76%   -35.20%     
================================================================
  Files                              303       10      -293     
  Lines                             7783      658     -7125     
  Branches                           501      119      -382     
================================================================
- Hits                              7624      413     -7211     
- Misses                             158      192       +34     
- Partials                             1       53       +52     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	?

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Impacted Files	Coverage Δ
...ain/java/org/opensearch/sql/analysis/Analyzer.java
...request/system/OpenSearchDescribeIndexRequest.java
...ch/sql/opensearch/response/OpenSearchResponse.java
...pensearch/sql/sql/parser/AstExpressionBuilder.java
...ql/opensearch/storage/OpenSearchStorageEngine.java
...ript/aggregation/dsl/AggregationBuilderHelper.java
...nsearch/sql/planner/physical/RareTopNOperator.java
...ch/sql/data/utils/NullsFirstExprValueOrdering.java
.../filter/lucene/relevance/MatchBoolPrefixQuery.java
...ch/planner/logical/rule/MergeLimitAndRelation.java
... and 303 more

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