feat: iOS Support

[Swatinem]

Very much WIP right now.

Things we need:

• getting CLI builds running on CI
• Make the crashpad backend work without a handler, and rather use the iOS only StartCrashpadInProcessHandler API.
• create a transport specifically for iOS, using the native http/s APIs
• get automated integration tests working somehow

[getsantry]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you remove the label Waiting for: Community, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀