Attach ttid/ttfd contributing flags

[markushi]

📜 Description

Left to do:

• define the actual name of the span attributes, right now it's "ttid.contributing" and "ttfd.contributing"
• ensure it's ok to only set the flag when it's true
• update dev docs

💡 Motivation and Context

Fixes #3252

💚 How did you test it?

Added 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

[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

- Attach ttid/ttfd contributing flags ([#3256](https://github.com/getsentry/sentry-java/pull/3256))

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 bea608b

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	382.69 ms	453.84 ms	71.15 ms
Size	1.70 MiB	2.28 MiB	592.39 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
4e260b3	378.73 ms	454.18 ms	75.45 ms
4bf95dd	345.96 ms	414.24 ms	68.28 ms
0bd723b	395.44 ms	472.66 ms	77.22 ms
7275aa8	422.39 ms	456.94 ms	34.55 ms
baaf637	375.71 ms	441.58 ms	65.87 ms
7eccfdb	366.98 ms	440.27 ms	73.29 ms
937879e	417.64 ms	550.45 ms	132.81 ms
9119d59	407.12 ms	509.64 ms	102.52 ms
93a76ca	378.48 ms	451.78 ms	73.30 ms
93a76ca	377.96 ms	447.52 ms	69.56 ms

App size

Revision	Plain	With Sentry	Diff
4e260b3	1.72 MiB	2.27 MiB	554.95 KiB
4bf95dd	1.72 MiB	2.29 MiB	576.40 KiB
0bd723b	1.72 MiB	2.29 MiB	578.09 KiB
7275aa8	1.70 MiB	2.28 MiB	590.71 KiB
baaf637	1.72 MiB	2.27 MiB	558.42 KiB
7eccfdb	1.72 MiB	2.27 MiB	556.93 KiB
937879e	1.72 MiB	2.27 MiB	558.42 KiB
9119d59	1.70 MiB	2.27 MiB	583.84 KiB
93a76ca	1.72 MiB	2.29 MiB	576.75 KiB
93a76ca	1.72 MiB	2.29 MiB	576.75 KiB