Refactor app hang and native crash apis to FFI/JNI

[buenaflor]

📜 Description

Part of FFI/JNI refactors

💡 Motivation and Context

Closes #3207

💚 How did you test it?

Unit test, manual tests

📝 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

[github-actions]

🚨 Detected changes in high risk code 🚨

High-risk code has higher potential to break the SDK and may be hard to test. To prevent severe bugs, apply the rollout process for releasing such changes and be extra careful when changing and reviewing these files:

• packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.31%. Comparing base (1ffba6f) to head (f881241).
⚠️ Report is 4 commits behind head on enh/app-start-refresh-rate-jni-ffi.

Files with missing lines	Patch %	Lines
.../flutter/lib/src/native/sentry_native_channel.dart	0.00%	3 Missing ⚠️

Additional details and impacted files

@@                          Coverage Diff                           @@
##           enh/app-start-refresh-rate-jni-ffi    #3289      +/-   ##
======================================================================
- Coverage                               89.46%   88.31%   -1.16%     
======================================================================
  Files                                      99       99              
  Lines                                    3523     3534      +11     
======================================================================
- Hits                                     3152     3121      -31     
- Misses                                    371      413      +42     

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[denrase]

LGTM 👍