enh: use lifecycle hook for before send event

[buenaflor]

📜 Description

Now that we have sdk lifecycle hooks we can re-factor the beforeSendEvent observer that we added to implement web sessions

💡 Motivation and Context

💚 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.

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

- use lifecycle hook for before send event ([#3017](https://github.com/getsentry/sentry-dart/pull/3017))

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 9e774c1

[codecov]

Codecov Report

Attention: Patch coverage is 36.66667% with 19 lines in your changes missing coverage. Please review.

Project coverage is 87.87%. Comparing base (b6c8720) to head (9e774c1).

Files with missing lines	Patch %	Lines
dart/lib/src/sentry_client.dart	37.50%	5 Missing ⚠️
dart/lib/src/hub.dart	0.00%	4 Missing ⚠️
dart/lib/src/hub_adapter.dart	0.00%	4 Missing ⚠️
dart/lib/src/noop_hub.dart	0.00%	3 Missing ⚠️
.../lib/src/integrations/web_session_integration.dart	66.66%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3017      +/-   ##
==========================================
- Coverage   87.97%   87.87%   -0.11%     
==========================================
  Files         287      287              
  Lines        9533     9541       +8     
==========================================
- Hits         8387     8384       -3     
- Misses       1146     1157      +11     

☔ View full report in Codecov by Sentry.
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[github-actions]

iOS Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1263.31 ms	1280.24 ms	16.93 ms
Size	7.86 MiB	9.44 MiB	1.58 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
827bf09	1261.86 ms	1276.41 ms	14.55 ms
c8596a6	1234.11 ms	1241.19 ms	7.08 ms
73dca78	1246.65 ms	1265.42 ms	18.76 ms
93b7728	1247.23 ms	1264.87 ms	17.64 ms
b6c8720	1252.65 ms	1266.61 ms	13.96 ms
2d34233	1258.19 ms	1268.92 ms	10.73 ms
6ba4675	1223.12 ms	1238.17 ms	15.04 ms

App size

Revision	Plain	With Sentry	Diff
827bf09	7.86 MiB	9.44 MiB	1.58 MiB
c8596a6	7.86 MiB	9.44 MiB	1.58 MiB
73dca78	7.86 MiB	9.44 MiB	1.58 MiB
93b7728	7.86 MiB	9.44 MiB	1.58 MiB
b6c8720	7.86 MiB	9.44 MiB	1.58 MiB
2d34233	7.86 MiB	9.44 MiB	1.58 MiB
6ba4675	7.86 MiB	9.44 MiB	1.58 MiB

Previous results on branch: enhancements/use-lifecycle-hook-before-send-event

Startup times

Revision	Plain	With Sentry	Diff
9d51684	1245.62 ms	1249.02 ms	3.40 ms
4e720b9	1265.15 ms	1272.98 ms	7.83 ms
e052838	1254.76 ms	1263.79 ms	9.04 ms

App size

Revision	Plain	With Sentry	Diff
9d51684	7.85 MiB	9.45 MiB	1.59 MiB
4e720b9	7.85 MiB	9.45 MiB	1.59 MiB
e052838	7.85 MiB	9.45 MiB	1.59 MiB

[github-actions]

Android Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	458.33 ms	486.46 ms	28.12 ms
Size	6.54 MiB	7.69 MiB	1.15 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
6ba4675	499.80 ms	632.43 ms	132.63 ms
2d34233	470.54 ms	558.90 ms	88.36 ms
73dca78	476.53 ms	522.21 ms	45.68 ms
b6c8720	457.41 ms	519.04 ms	61.63 ms
93b7728	475.28 ms	489.13 ms	13.86 ms
c8596a6	474.00 ms	492.96 ms	18.96 ms
827bf09	475.40 ms	547.14 ms	71.74 ms

App size

Revision	Plain	With Sentry	Diff
6ba4675	6.54 MiB	7.53 MiB	1015.26 KiB
2d34233	6.54 MiB	7.55 MiB	1.01 MiB
73dca78	6.54 MiB	7.69 MiB	1.15 MiB
b6c8720	6.54 MiB	7.69 MiB	1.15 MiB
93b7728	6.54 MiB	7.69 MiB	1.15 MiB
c8596a6	6.54 MiB	7.53 MiB	1015.27 KiB
827bf09	6.54 MiB	7.53 MiB	1015.27 KiB

Previous results on branch: enhancements/use-lifecycle-hook-before-send-event

Startup times

Revision	Plain	With Sentry	Diff
9d51684	517.34 ms	569.74 ms	52.40 ms
4e720b9	469.48 ms	517.15 ms	47.67 ms
e052838	457.27 ms	485.24 ms	27.97 ms

App size

Revision	Plain	With Sentry	Diff
9d51684	6.54 MiB	7.53 MiB	1017.60 KiB
4e720b9	6.54 MiB	7.53 MiB	1017.60 KiB
e052838	6.54 MiB	7.53 MiB	1017.60 KiB

[buenaflor]

@denrase can you have a early look pls