feat: add support for custom patch delimiters in PatchDocumentOptions

[venkateshwarreddyr]

Resolves: #2972

What does this PR do?

Adds support for customizable placeholder delimiters in the patchDocument function.

This allows users to define delimiters other than {{ }}, such as << >>, { }, or any custom format.

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Why is this needed?

Currently, the placeholder syntax is hardcoded to use {{ }}. This enhancement enables more flexibility when using different template styles or avoiding syntax collisions.

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How does it work?

• Added an optional placeholderDelimiters field to PatchDocumentOptions.
• Fallback to default delimiters {{ and }} if none provided.
• Adjusted how patchText is built.
• Updated types to include readonly as per lint rules.
• Added test cases to cover custom delimiters and edge cases.

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Screenshots / Test Evidence

✅ Added tests for:

• default delimiters
• custom delimiters: {{}}
• error on empty string delimiters

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Checklist

• I’ve added/updated tests
• I’ve run npm run lint
• I’ve run npm run test
• Code follows existing style guidelines
• PR title uses conventional commit format (feat:, fix:, etc.)

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Let me know if you'd like any changes!

[venkateshwarreddyr]

Feature request: #2972

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (8ba9a44) to head (3a96018).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #3036   +/-   ##
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  Coverage   100.00%   100.00%           
=========================================
  Files          290       290           
  Lines         8764      8769    +5     
  Branches      1413      1421    +8     
=========================================
+ Hits          8764      8769    +5     

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