Replace Android thread id with kernel thread id in span data

[stefanosiano]

📜 Description

renamed IMainThreadChecker to IThreadChecker
added getCurrentThreadSystemId() to IThreadChecker
replaced thread id of SentryTracer and PerformanceAndroidEventProcessor

Adding to v8, since it's a behavioural change and users could already use it in some dashboard, as it's indexed. This is very unlikely, though.

💡 Motivation and Context

Continuous profiler needs to bind the trace and span to the corresponding thread in the profile.
The Android profiler retrieves the kernel thread id, that we can get via Process.myTid(), so we have to set that instead of Thread.getThreadId()

💚 How did you test it?

📝 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

[stefanosiano]

Most changes come from renaming IMainThreadChecker to IThreadChecker.
I can revert the renaming if you like it more

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	437.31 ms	452.81 ms	15.50 ms
Size	1.70 MiB	2.35 MiB	667.30 KiB

Previous results on branch: enh/android-kernel-thread-id

Startup times

Revision	Plain	With Sentry	Diff
e312dff	436.72 ms	491.35 ms	54.63 ms

App size

Revision	Plain	With Sentry	Diff
e312dff	1.70 MiB	2.35 MiB	667.25 KiB

[romtsn]

LGTM, just a couple of comments around mainThreadId