feat(bigquery): handle duplicate job error with jobs.insert

[alvarowolfx]

A transport/io error can happen after query was inserted and RPC level retries might try to re-insert it with same job ID. Instead of re running the query, we can connect to the existing one to avoid running and billing a new query.

Towards #6218 #6717

[gemini-code-assist]

Code Review

This pull request introduces handling for duplicate job errors during BigQuery query execution. When a duplicate job error is encountered, the client now attempts to adopt the existing job instead of failing. This is achieved by retrieving the existing job and checking its status. Additionally, the PR includes comprehensive unit tests to verify this new behavior. I have no further feedback to provide as there are no review comments.

[codecov]

Codecov Report

❌ Patch coverage is 97.91667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.02%. Comparing base (8fb991a) to head (2860a3d).
⚠️ Report is 18 commits behind head on main.

Files with missing lines	Patch %	Lines
src/bigquery/src/query/execution.rs	97.89%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6799      +/-   ##
==========================================
- Coverage   97.03%   97.02%   -0.01%     
==========================================
  Files         326      326              
  Lines      107511   107597      +86     
==========================================
+ Hits       104322   104399      +77     
- Misses       3189     3198       +9     

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