feat(js-sdk): support release health

[buenaflor]

📜 Description

Built on top of PR #2489

💡 Motivation and Context

Adds support for sessions / release health.

💚 How did you test it?

📝 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]

	Fails
🚫	Please consider adding a changelog entry for the next release.

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Instructions and example for changelog

Please add an entry to CHANGELOG.md to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:

## Unreleased

- support release health ([#2546](https://github.com/getsentry/sentry-dart/pull/2546))

If none of the above apply, you can opt out of this check by adding #skip-changelog to the PR description.

Generated by 🚫 dangerJS against a60012f

[codecov]

Codecov Report

Attention: Patch coverage is 84.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 88.12%. Comparing base (be08651) to head (a60012f).
Report is 69 commits behind head on feat/js-sdk-integration.

Files with missing lines	Patch %	Lines
flutter/lib/src/native/c/sentry_native.dart	33.33%	2 Missing ⚠️
flutter/lib/src/native/sentry_native_channel.dart	0.00%	2 Missing ⚠️

Additional details and impacted files

@@                     Coverage Diff                      @@
##           feat/js-sdk-integration    #2546       +/-   ##
============================================================
+ Coverage                    70.98%   88.12%   +17.14%     
============================================================
  Files                           17      119      +102     
  Lines                          579     4397     +3818     
============================================================
+ Hits                           411     3875     +3464     
- Misses                         168      522      +354     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[bruno-garcia]

the definition of session in JS is about to change on v9
might be a good idea to line it up, so only ship the Dart on JS session using the v9 sdk. you could piggy back on their alpha to ship your on alphas etc

[bruno-garcia]

Is this change needed to be part of the web support? it could have side effects of itself worth tracking as a separate change probably done before the big web support.

[buenaflor]

this is temporary for testing, on web with the js sdk integration this seems to run into a recursion so I've disabled it for now I will revert it back after I fixed the issue

[buenaflor]

note: currently the PR that this is based on is not merged yet so bunch of unrelated changes will show up for now