Support Crashpad on iOS

[jan-auer]

Crashpad builds, now we need to get the SDK working.

[bruno-garcia]

@jan-auer there seems to be a huge gap for us here. No one from our team can get this done easily. If you can pair up with one of us, we can get this done. Until there we're not moving forward with this.

[Swatinem]

So, I started updating the build system and backend for ios crashpad here:
#436 progress is okay…

But I think we started with a completely wrong understanding that crashpad on iOS is actually ready, which I think it is not.

The only API currently exposed by iOS takes no database or url, and also the crashpad tests for iOS don’t have any assertions in them:

https://github.com/getsentry/crashpad/blob/a26ad17363f7f292b6ed1c382717b0d1928d4555/client/crashpad_client_ios.cc#L213-L219

https://github.com/getsentry/crashpad/blob/a26ad17363f7f292b6ed1c382717b0d1928d4555/test/ios/crash_type_xctest.mm#L68-L82

That said, I have no idea what crashpad is actually doing, but I can tell you what it is not doing: giving you an API with which you can actually inspect crashes after the fact.

[DrProfesor]

Supporting iOS in the native SDK would be super helpful for cross platform projects so that developers won't need to integrate and maintain multiple Sentry SDKs.