add escape method for process function

[ylwu-amzn]

Description

Add escape method for process function to make it easier to escape string in pre/post process function.

Issues Resolved

[List any issues this PR will resolve]

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

Attention: 12 lines in your changes are missing coverage. Please review.

Comparison is base (50d30df) 82.59% compared to head (2995780) 82.60%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
.../preprocess/RemoteInferencePreProcessFunction.java	36.36%	6 Missing and 1 partial ⚠️
...ch/ml/engine/algorithms/remote/ConnectorUtils.java	0.00%	4 Missing ⚠️
...va/org/opensearch/ml/common/utils/StringUtils.java	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #2053   +/-   ##
=========================================
  Coverage     82.59%   82.60%           
- Complexity     5604     5613    +9     
=========================================
  Files           542      542           
  Lines         22549    22574   +25     
  Branches       2293     2300    +7     
=========================================
+ Hits          18625    18647   +22     
- Misses         2989     2993    +4     
+ Partials        935      934    -1     

Flag	Coverage Δ
ml-commons	82.60% <80.32%> (+<0.01%)	⬆️

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