Hubs/Scopes Merge 37 - Fix combined `Contexts`

[adinauer]

#skip-changelog

:scroll: Description

We extended ConcurrentHashMap, exposing lots of stuff as public API and making it hard to combine Contexts. I've now moved this map into a property we forward to. We can add additional API that was there with the map extension if needed.

:bulb: Motivation and Context

:green_heart: How did you test it?

:pencil: 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.

:crystal_ball: Next steps

[github-actions[bot]]

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

Generated by :no_entry_sign: dangerJS against dc35d9974225b2b2cd0084902125adbc64c5ebae

[github-actions[bot]]

Performance metrics :rocket:

	Plain	With Sentry	Diff
Startup time	388.74 ms	475.12 ms	86.38 ms
Size	1.70 MiB	2.28 MiB	595.19 KiB

Previous results on branch: feat/hsm-37-combined-contexts

Startup times

Revision	Plain	With Sentry	Diff
428a5c2550e8de1566d6e38669aef0467bfd917e	418.30 ms	498.73 ms	80.43 ms

App size

Revision	Plain	With Sentry	Diff
428a5c2550e8de1566d6e38669aef0467bfd917e	1.70 MiB	2.28 MiB	595.19 KiB