Update native SDKs

[sc85]

The Android SDK was not up to date. I updated it to sentry-android 2.0.2 which came with some required changes. In addition I also updated the iOS SDK.

BREAKING CHANGES:

• On Android Extras now get stringified before sent to the Sentry API. I could not find any other way.
• The DSN needs to be added to the AndroidManifest (see README.md) since the I found no way to call the new native init method which expects a Lamda function

[sc85]

Closing this and reopening it with different branch.