Add reverse() string function to V2

[margarit-h]

• Add reverse() string function to V2

Signed-off-by: Margarit Hakobyan margarith@bitquilltech.com

Description

Usage: REVERSE(str) returns reversed string of the string supplied as an argument. Returns NULL if the argument is NULL.

Argument type: STRING

Return type: STRING

Example::

os> SELECT REVERSE('abcde')
fetched rows / total rows = 1/1
+--------------------+
| REVERSE('abcde')   |
|--------------------|
| edcba              |
+--------------------+

Example::

os> source=people | eval `REVERSE('abcde')` = REVERSE('abcde') | fields `REVERSE('abcde')`
fetched rows / total rows = 1/1
+--------------------+
| REVERSE('abcde')   |
|--------------------|
| edcba              |
+--------------------+

Issues Resolved

[List any issues this PR will resolve]

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.

[dai-chen]

Thanks for the changes!

[codecov-commenter]

Codecov Report

Merging #1154 (2da8408) into 2.x (2af7321) will decrease coverage by 2.49%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                2.x    #1154      +/-   ##
============================================
- Coverage     98.30%   95.81%   -2.50%     
- Complexity     3518     3521       +3     
============================================
  Files           342      352      +10     
  Lines          8694     9358     +664     
  Branches        554      673     +119     
============================================
+ Hits           8547     8966     +419     
- Misses          142      334     +192     
- Partials          5       58      +53     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	98.31% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
...c/main/java/org/opensearch/sql/expression/DSL.java	100.00% <100.00%> (ø)
...h/sql/expression/function/BuiltinFunctionName.java	100.00% <100.00%> (ø)
...g/opensearch/sql/expression/text/TextFunction.java	100.00% <100.00%> (ø)
workbench/public/components/Main/main.tsx	53.00% <0.00%> (ø)
workbench/public/components/PPLPage/PPLPage.tsx	56.52% <0.00%> (ø)
...ch/public/components/QueryResults/QueryResults.tsx	61.60% <0.00%> (ø)
...ublic/components/QueryResults/QueryResultsBody.tsx	68.32% <0.00%> (ø)
workbench/public/components/app.tsx	0.00% <0.00%> (ø)
...h/public/components/QueryLanguageSwitch/Switch.tsx	85.71% <0.00%> (ø)
workbench/public/utils/PanelWrapper.tsx	100.00% <0.00%> (ø)
... and 3 more

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