feat(metrics): Add timing API

[philipphofmann]

📜 Description

Add the timing API to measure the duration of a closure.

💡 Motivation and Context

Part of #3790.

💚 How did you test it?

Unit tests and with a simulator. Here is an example in Sentry https://sentry-sdks.sentry.io/performance/sentry-cocoa:94a719e3ebbe444fac10279e60795f3c/#span-0af24f27f2674bef.

📝 Checklist

You have to check all boxes before merging:

• 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 7e691d7

[codecov]

Codecov Report

Attention: Patch coverage is 96.63866% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 90.890%. Comparing base (5e769dd) to head (7e691d7).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3812       +/-   ##
=============================================
- Coverage   90.947%   90.890%   -0.058%     
=============================================
  Files          560       560               
  Lines        44186     44281       +95     
  Branches     15764     15812       +48     
=============================================
+ Hits         40186     40247       +61     
+ Misses        3930      3854       -76     
- Partials        70       180      +110     

Files	Coverage Δ
Sources/Swift/Metrics/SentryMetricsAPI.swift	100.000% <100.000%> (ø)
Sources/Sentry/SentryHub.m	98.516% <75.000%> (-0.297%)	⬇️
...tryTests/Swift/Metrics/SentryMetricsAPITests.swift	97.385% <96.739%> (-2.615%)	⬇️

... and 32 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1221.38 ms	1246.28 ms	24.90 ms
Size	21.58 KiB	573.16 KiB	551.58 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
e84bc3f	1257.08 ms	1267.41 ms	10.33 ms
e1cd9e9	1203.93 ms	1239.12 ms	35.19 ms
32e64d1	1224.45 ms	1238.94 ms	14.49 ms
be2977c	1202.51 ms	1221.32 ms	18.81 ms
8c8654d	1214.43 ms	1223.88 ms	9.45 ms
db533ee	1228.96 ms	1248.23 ms	19.28 ms
3f366ee	1242.28 ms	1260.80 ms	18.52 ms
4654f66	1247.16 ms	1263.96 ms	16.80 ms
189b629	1250.64 ms	1261.02 ms	10.38 ms
d10ae0c	1250.02 ms	1253.74 ms	3.72 ms

App size

Revision	Plain	With Sentry	Diff
e84bc3f	20.76 KiB	434.72 KiB	413.96 KiB
e1cd9e9	22.85 KiB	412.95 KiB	390.10 KiB
32e64d1	20.76 KiB	433.18 KiB	412.42 KiB
be2977c	22.85 KiB	407.67 KiB	384.83 KiB
8c8654d	22.84 KiB	403.18 KiB	380.33 KiB
db533ee	21.58 KiB	547.02 KiB	525.44 KiB
3f366ee	20.76 KiB	427.84 KiB	407.08 KiB
4654f66	20.76 KiB	432.17 KiB	411.41 KiB
189b629	20.76 KiB	399.69 KiB	378.93 KiB
d10ae0c	20.76 KiB	419.86 KiB	399.10 KiB

Previous results on branch: feat/metrics-timing

Startup times

Revision	Plain	With Sentry	Diff
7b94ee8	1337.94 ms	1362.88 ms	24.94 ms

App size

Revision	Plain	With Sentry	Diff
7b94ee8	21.58 KiB	574.29 KiB	552.71 KiB

[brustolin]

LGTM