ENH: Enhance PDF Merging Capabilities for Nested Bookmarks - Addresses Issue #2305

[mrishav]

This PR addresses Issue #2305 by enhancing the PDF merging capabilities of PyPDF, specifically focusing on the handling of nested bookmarks.

Changes Made:

• Modification to Existing Merging Logic: The merging functions in pypdf/generic/__init__.py have been updated to better manage nested bookmarks. This ensures that the hierarchical structure of bookmarks is maintained accurately during the merge process.
• New File Addition (_annotation_formats.py): Introduced a new module to support additional annotation formats. This enhancement aids in the preservation of annotations during the merging process, ensuring that no data is lost and annotations are correctly aligned in the merged document.

[codecov]

Codecov Report

Attention: Patch coverage is 9.37500% with 29 lines in your changes are missing coverage. Please review.

Project coverage is 94.59%. Comparing base (1d8d3be) to head (e3a55a5).

Files	Patch %	Lines
pypdf/generic/_annotation_formats.py	0.00%	23 Missing ⚠️
pypdf/generic/__init__.py	33.33%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2603      +/-   ##
==========================================
- Coverage   94.92%   94.59%   -0.33%     
==========================================
  Files          50       51       +1     
  Lines        8316     8348      +32     
  Branches     1667     1673       +6     
==========================================
+ Hits         7894     7897       +3     
- Misses        261      290      +29     
  Partials      161      161              

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[stefan6419846]

Thanks for the PR. Could you please fix the formatting and add corresponding tests to ensure that (preferably) all your changes are covered accordingly?

[pubpub-zz]

@mrishav
The annotation builder is under deprecation process in favor of https://pypdf.readthedocs.io/en/stable/user/adding-pdf-annotations.html

Can you review the new approach to confirm the issue or not.

Also can you add documentation for your added code.