Report Flutter framework feature flags

[ueman]

📜 Description

There's a Flutter framework (draft) PR that adds feature flags to Flutter itself.
This PR supports that

💡 Motivation and Context

I want know whether a specific build used one of the feature flags.

💚 How did you test it?

I didn't. I'm not really sure how to even test this with a non-flaky test.

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• No new PII added or SDK only sends newly added PII if sendDefaultPii is enabled
• I updated the docs if needed
• All tests passing
• No breaking changes

🔮 Next steps

I'll keep this a draft until the linked PR is merged for some time. Afterwards this PR can be landed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.09%. Comparing base (3925712) to head (23deec5).

❗ There is a different number of reports uploaded between BASE (3925712) and HEAD (23deec5). Click for more details.

HEAD has 8 uploads less than BASE

Flag	BASE (3925712)	HEAD (23deec5)
	9	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2991       +/-   ##
===========================================
- Coverage   87.63%   63.09%   -24.55%     
===========================================
  Files         278        4      -274     
  Lines        9180      168     -9012     
===========================================
- Hits         8045      106     -7939     
+ Misses       1135       62     -1073     

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