Kw/app start span for hybrid SDKs

[krystofwoldrich]

📜 Description

This PR adds a new method to the HybridSDKs interface which returns serializable app start data including span structures.

This can be used in Flutter (replacing current custom impl), React Native and other hybrid SDKs like Unity, Capacitor and others.

💡 Motivation and Context

• Load detailed app start spans from native SDKs sentry-react-native#3445

💚 How did you test it?

unit tests

📝 Checklist

• I reviewed the submitted code.
• 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.
• 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

#skip-changelog

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	389.53 ms	468.83 ms	79.30 ms
Size	1.70 MiB	2.28 MiB	592.12 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
d6d2b2e	392.55 ms	467.50 ms	74.95 ms
c7e2fbc	393.98 ms	478.24 ms	84.27 ms
4e260b3	388.40 ms	468.98 ms	80.58 ms
28c9a83	366.20 ms	433.88 ms	67.67 ms
baaf637	418.39 ms	496.86 ms	78.47 ms
283d83e	416.81 ms	497.22 ms	80.41 ms
283d83e	348.44 ms	392.06 ms	43.62 ms
0bf143e	368.35 ms	437.47 ms	69.12 ms
86f0096	368.63 ms	446.92 ms	78.29 ms
619c9b9	428.23 ms	514.66 ms	86.43 ms

App size

Revision	Plain	With Sentry	Diff
d6d2b2e	1.72 MiB	2.27 MiB	555.05 KiB
c7e2fbc	1.72 MiB	2.29 MiB	576.40 KiB
4e260b3	1.72 MiB	2.27 MiB	554.95 KiB
28c9a83	1.70 MiB	2.28 MiB	592.00 KiB
baaf637	1.72 MiB	2.27 MiB	558.42 KiB
283d83e	1.72 MiB	2.29 MiB	577.69 KiB
283d83e	1.72 MiB	2.29 MiB	577.69 KiB
0bf143e	1.72 MiB	2.29 MiB	576.50 KiB
86f0096	1.72 MiB	2.29 MiB	576.50 KiB
619c9b9	1.70 MiB	2.28 MiB	592.12 KiB

Previous results on branch: kw/appStartSpanForHybridSDKs

Startup times

Revision	Plain	With Sentry	Diff
27c9de3	368.88 ms	473.28 ms	104.40 ms
c9f1bb9	417.57 ms	476.24 ms	58.67 ms
d52f826	430.57 ms	475.76 ms	45.19 ms

App size

Revision	Plain	With Sentry	Diff
27c9de3	1.70 MiB	2.28 MiB	592.12 KiB
c9f1bb9	1.70 MiB	2.28 MiB	592.12 KiB
d52f826	1.70 MiB	2.28 MiB	592.12 KiB

[krystofwoldrich]

@buenaflor This the same app start helper as for iOS. Again, please review the code from Flutter point of view.

[markushi]

Nice one, looks good! Please have a look at my comments, especially the one about accepting only valid timespans.

[buenaflor]

works on flutter 👍 looks good to me