feat(Data Modeling, Files): Extend DM Files with all download methods

[haakonvt]

Part 2 out of 4.

PR stacked on #2647

[gemini-code-assist]

Code Review

This pull request implements file download and download URL retrieval capabilities (retrieve_download_urls, download, download_to_path, and download_bytes) for the data modeling files API in both async and sync clients. The feedback focuses on a potential breaking change introduced by renaming the nodes parameter to node_ids in the retrieve method of the data modeling files API. The reviewer recommends reverting this parameter name back to nodes across all overloads, implementation signatures, docstrings, and internal calls to maintain backward compatibility for keyword-argument callers.

[codecov]

Codecov Report

❌ Patch coverage is 80.48780% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.06%. Comparing base (a09f5dd) to head (2df4d92).

Files with missing lines	Patch %	Lines
cognite/client/_api/data_modeling/files.py	60.00%	4 Missing ⚠️
cognite/client/_sync_api/data_modeling/files.py	60.00%	4 Missing ⚠️

Additional details and impacted files

@@                        Coverage Diff                         @@
##           add-files-api-to-data-modeling    #2653      +/-   ##
==================================================================
- Coverage                           93.08%   93.06%   -0.02%     
==================================================================
  Files                                 489      489              
  Lines                               49879    49911      +32     
==================================================================
+ Hits                                46428    46450      +22     
- Misses                               3451     3461      +10     

Files with missing lines	Coverage Δ
cognite/client/_api/files.py	94.08% <100.00%> (+0.15%)	⬆️
cognite/client/_sync_api/files.py	100.00% <100.00%> (ø)
tests/tests_integration/test_api/test_files.py	95.83% <100.00%> (+0.03%)	⬆️
cognite/client/_api/data_modeling/files.py	93.33% <60.00%> (-6.67%)	⬇️
cognite/client/_sync_api/data_modeling/files.py	87.87% <60.00%> (-12.13%)	⬇️

... and 3 files with indirect coverage changes

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