feat: add headers field to InfluxDBError and add example of use

[karel-rehor]

Proposed Changes

• Also add headers field to InfluxDBError (headers are already in rest.py class ApiException).
• Add asserts for headers in existing tests
• Add test of headers field
• Add http_error_handling.py example

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• pytest tests completes successfully
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.47%. Comparing base (45e6607) to head (db7df20).
Report is 9 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #665      +/-   ##
==========================================
+ Coverage   90.43%   90.47%   +0.03%     
==========================================
  Files          40       40              
  Lines        3524     3526       +2     
==========================================
+ Hits         3187     3190       +3     
+ Misses        337      336       -1     

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[bednar]

Thanks for your PR 👍

LGTM 🚀