Allow users to set metadata for BoAmps

[benoit-cty]

Description

Allow users to set metadata for BoAmps.

Motivation and Context

BoAmps has required semantic fields (taskStage, taskFamily, algorithms, dataset) that CodeCarbon cannot infer automatically.

So users needed a way to provide BoAmps context manually.

Before this PR it was possible to do it but harder :

• Build a BoAmpsOutput with custom context (task/header/quality), or load it from a JSON file.
• Pass that handler in output_handlers when creating EmissionsTracker or OfflineEmissionsTracker.
• Let the tracker call that handler at stop/flush time.

What changed now:

• You can still do it that way.
• But the preferred, simpler path is the new generic metadata parameter, where BoAmps reads metadata["boamps"].

How Has This Been Tested?

With the updated example examples/boamps_output.py

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

AI Usage Disclosure

Please refer to docs/how-to/ai-policy.md for detailed guidelines on how to disclose AI usage in your PR. Accurately completing this section is mandatory.

• 🟥 AI-vibecoded: You cannot explain the logic. Car analogy : the car drive by itself, you are outside it and just tell it where to go.
• 🟠 AI-generated: Car analogy : the car drive by itself, you are inside and give instructions.
• ⭐ AI-assisted. Car analogy : you drive the car, AI help you find your way.
• ♻️ No AI used. Car analogy : you drive the car.

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the docs/how-to/contributing.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

❌ Patch coverage is 92.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.19%. Comparing base (abfdd8c) to head (db9ea2e).

Files with missing lines	Patch %	Lines
codecarbon/emissions_tracker.py	90.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1234      +/-   ##
==========================================
+ Coverage   89.18%   89.19%   +0.01%     
==========================================
  Files          47       47              
  Lines        4511     4535      +24     
==========================================
+ Hits         4023     4045      +22     
- Misses        488      490       +2     

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