feat: add sample_rand / fix sample_rate in baggage

[philprime]

📜 Description

• Add sample_rand to the baggage
• Fixed sample_rate not added to baggage
• Add additional initializer tests for public interfaces

💡 Motivation and Context

See #4687

💚 How did you test it?

• I kept the original tests to make sure the behaviour doesn't change
• I added a lot of additional tests to ensure a stable API for the public headers
• Used guidance here: https://github.com/getsentry/projects/issues/316#issuecomment-2612117275
• CI
• Checked the envelope header using a proxy debugging tool

📝 Checklist

You have to check all boxes before merging:

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

• Perform integrations tests

[github-actions]

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

Generated by 🚫 dangerJS against 5e98ccf

[codecov]

Codecov Report

Attention: Patch coverage is 99.53024% with 8 lines in your changes missing coverage. Please review.

Project coverage is 91.390%. Comparing base (70c49ca) to head (5e98ccf).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/Sentry/Profiling/SentryLaunchProfiling.m	73.913%	6 Missing ⚠️
Sources/Sentry/SentrySampling.m	84.615%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4751       +/-   ##
=============================================
+ Coverage   91.101%   91.390%   +0.288%     
=============================================
  Files          626       627        +1     
  Lines        72769     74419     +1650     
  Branches     25866     26755      +889     
=============================================
+ Hits         66294     68012     +1718     
+ Misses        6382      6310       -72     
- Partials        93        97        +4     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryBaggage.m	100.000% <100.000%> (ø)
Sources/Sentry/SentryBuildAppStartSpans.m	100.000% <ø> (ø)
Sources/Sentry/SentryHub.m	97.981% <100.000%> (+0.018%)	⬆️
Sources/Sentry/SentrySamplerDecision.m	100.000% <100.000%> (ø)
Sources/Sentry/SentryTraceContext.m	96.644% <100.000%> (+2.289%)	⬆️
Sources/Sentry/SentryTransactionContext.mm	100.000% <100.000%> (ø)
...yProfilerTests/SentryAppLaunchProfilingTests.swift	100.000% <100.000%> (ø)
...SentryProfilerTests/SentryProfileTestFixture.swift	99.704% <100.000%> (+<0.001%)	⬆️
...ts/SentryTests/Helper/SentryFileManagerTests.swift	96.275% <100.000%> (+0.155%)	⬆️
.../SentryTests/Helper/SentrySerializationTests.swift	99.807% <100.000%> (+0.010%)	⬆️
... and 9 more

... and 24 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1225.77 ms	1248.69 ms	22.92 ms
Size	22.31 KiB	780.61 KiB	758.29 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
eea25a8	1240.54 ms	1262.69 ms	22.15 ms
ed64658	1225.06 ms	1247.73 ms	22.67 ms
2d2068d	1238.02 ms	1249.90 ms	11.88 ms
489fbb8	1238.67 ms	1265.66 ms	26.99 ms
4977fbc	1231.55 ms	1239.80 ms	8.25 ms
9ce54cc	1217.79 ms	1239.42 ms	21.63 ms
ce54c6a	1237.02 ms	1241.02 ms	4.00 ms
522f8da	1230.19 ms	1252.31 ms	22.12 ms
f8833c4	1230.00 ms	1245.27 ms	15.27 ms
a90f228	1226.37 ms	1248.63 ms	22.27 ms

App size

Revision	Plain	With Sentry	Diff
eea25a8	22.31 KiB	771.26 KiB	748.94 KiB
ed64658	22.30 KiB	749.84 KiB	727.54 KiB
2d2068d	21.58 KiB	729.47 KiB	707.89 KiB
489fbb8	21.90 KiB	730.10 KiB	708.20 KiB
4977fbc	20.76 KiB	419.86 KiB	399.10 KiB
9ce54cc	21.58 KiB	573.72 KiB	552.13 KiB
ce54c6a	21.58 KiB	418.60 KiB	397.02 KiB
522f8da	21.90 KiB	726.18 KiB	704.28 KiB
f8833c4	21.58 KiB	422.66 KiB	401.08 KiB
a90f228	21.90 KiB	724.12 KiB	702.22 KiB

Previous results on branch: philprime/issue-4687-sampling-seed-propagation

Startup times

Revision	Plain	With Sentry	Diff
ab1ebcb	1214.52 ms	1235.14 ms	20.62 ms
f5ee173	1225.88 ms	1240.40 ms	14.52 ms
5400890	1230.16 ms	1243.23 ms	13.07 ms
544ce99	1216.27 ms	1227.33 ms	11.06 ms
a618a92	1221.79 ms	1242.41 ms	20.62 ms
abfb8ff	1226.31 ms	1245.65 ms	19.35 ms
63bb06c	1216.49 ms	1237.31 ms	20.82 ms
ca8ee23	1227.45 ms	1247.34 ms	19.89 ms

App size

Revision	Plain	With Sentry	Diff
ab1ebcb	22.31 KiB	777.76 KiB	755.45 KiB
f5ee173	22.31 KiB	780.37 KiB	758.05 KiB
5400890	22.31 KiB	776.94 KiB	754.62 KiB
544ce99	22.31 KiB	777.60 KiB	755.29 KiB
a618a92	22.31 KiB	777.65 KiB	755.34 KiB
abfb8ff	22.31 KiB	776.94 KiB	754.62 KiB
63bb06c	22.31 KiB	777.76 KiB	755.45 KiB
ca8ee23	22.31 KiB	775.60 KiB	753.29 KiB

[philprime]

Back to draft because I noticed missing test cases

[brustolin]

I do have one comment that I think would short this PR a lot.

[philipphofmann]

I will give this a full review once we remove the span changes, as this will significantly reduce the scope of the PR.

[philipphofmann]

LGTM, thanks for all the extra tests

[philipphofmann]

LGTM thanks.