Add before_emit_metric callback to options

[markushi]

📜 Description

💡 Motivation and Context

💚 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

[github-actions]

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

Generated by 🚫 dangerJS against 82ec8cd

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	387.36 ms	456.61 ms	69.25 ms
Size	1.70 MiB	2.28 MiB	592.01 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
0404ea3	332.47 ms	401.12 ms	68.66 ms
86f0096	381.33 ms	476.58 ms	95.25 ms
0bd723b	375.20 ms	452.41 ms	77.20 ms
b172d4e	352.92 ms	446.50 ms	93.58 ms
d007225	365.63 ms	438.24 ms	72.62 ms
93a76ca	381.08 ms	459.22 ms	78.14 ms
7ab32b6	373.62 ms	480.61 ms	106.99 ms
d6d2b2e	392.55 ms	467.50 ms	74.95 ms
baaf637	418.39 ms	496.86 ms	78.47 ms
8ff8fd0	432.77 ms	495.18 ms	62.41 ms

App size

Revision	Plain	With Sentry	Diff
0404ea3	1.72 MiB	2.29 MiB	577.52 KiB
86f0096	1.72 MiB	2.29 MiB	576.50 KiB
0bd723b	1.72 MiB	2.29 MiB	578.09 KiB
b172d4e	1.72 MiB	2.29 MiB	578.09 KiB
d007225	1.70 MiB	2.27 MiB	586.31 KiB
93a76ca	1.72 MiB	2.29 MiB	576.75 KiB
7ab32b6	1.70 MiB	2.27 MiB	584.63 KiB
d6d2b2e	1.72 MiB	2.27 MiB	555.05 KiB
baaf637	1.72 MiB	2.27 MiB	558.42 KiB
8ff8fd0	1.72 MiB	2.27 MiB	558.15 KiB

Previous results on branch: feat/metrics-before-emit-callback

Startup times

Revision	Plain	With Sentry	Diff
f67b430	406.96 ms	513.90 ms	106.94 ms
1fb10c6	396.13 ms	457.85 ms	61.73 ms

App size

Revision	Plain	With Sentry	Diff
f67b430	1.70 MiB	2.28 MiB	592.01 KiB
1fb10c6	1.70 MiB	2.28 MiB	592.01 KiB

[stefanosiano]

just minor detail in tests, but good!