Feat: Measure app start time

[marandaneto]

📜 Description

Feat: App start metric

💡 Motivation and Context

extract from #1466

💚 How did you test it?

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• No breaking changes

🔮 Next steps

[codecov-commenter]

Codecov Report

Merging #1487 (c43cb3e) into main (97c6a66) will decrease coverage by 0.11%.
The diff coverage is 63.15%.

@@             Coverage Diff              @@
##               main    #1487      +/-   ##
============================================
- Coverage     76.12%   76.00%   -0.12%     
- Complexity     1934     1942       +8     
============================================
  Files           191      192       +1     
  Lines          6696     6721      +25     
  Branches        666      668       +2     
============================================
+ Hits           5097     5108      +11     
- Misses         1274     1287      +13     
- Partials        325      326       +1     

Impacted Files	Coverage Δ
sentry/src/main/java/io/sentry/HubAdapter.java	5.17% <0.00%> (-0.10%)	⬇️
sentry/src/main/java/io/sentry/NoOpHub.java	48.71% <0.00%> (-1.29%)	⬇️
sentry/src/main/java/io/sentry/NoOpSpan.java	30.00% <0.00%> (-1.58%)	⬇️
...entry/src/main/java/io/sentry/NoOpTransaction.java	20.68% <0.00%> (-0.74%)	⬇️
sentry/src/main/java/io/sentry/Sentry.java	42.06% <0.00%> (-0.59%)	⬇️
...main/java/io/sentry/protocol/MeasurementValue.java	0.00% <0.00%> (ø)
sentry/src/main/java/io/sentry/IHub.java	90.47% <50.00%> (-4.53%)	⬇️
...ain/java/io/sentry/protocol/SentryTransaction.java	86.20% <50.00%> (-2.69%)	⬇️
sentry/src/main/java/io/sentry/Hub.java	73.20% <66.66%> (-0.13%)	⬇️
sentry/src/main/java/io/sentry/Span.java	90.56% <87.50%> (-1.44%)	⬇️
... and 2 more

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[philipphofmann]

The first pass. Looks already pretty good. 👍

[philipphofmann]

I think we are still missing tests validating the span creation of the ActivityLifecycleIntegration.

Nice seeing this going forward 🚀.

[philipphofmann]

Almost done 👍

[philipphofmann]

Thanks for adapting my suggested changes for the tests. 👍
LGTM 🚀