evalengine: Implement REPLACE

[dbussink]

This implements the REPLACE function. This function is documented as case sensitive, but in practice is also byte sensitive. This means that equal characters under collation rules are not replaced.

Related Issue(s)

Part of #9647

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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• Tests were added or are not required
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• Documentation was added or is not required

[vitess-bot]

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[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (54c6dfc) 67.44% compared to head (4bb44d8) 67.49%.

Files	Patch %	Lines
go/vt/vtgate/evalengine/fn_string.go	94.80%	4 Missing ⚠️
go/vt/vtgate/evalengine/translate_builtin.go	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15274      +/-   ##
==========================================
+ Coverage   67.44%   67.49%   +0.04%     
==========================================
  Files        1561     1561              
  Lines      193193   193297     +104     
==========================================
+ Hits       130304   130458     +154     
+ Misses      62889    62839      -50     

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[GuptaManan100]

LGTM