Add `RNSentrySDK` APIs support to `@sentry/react-native/expo` plugin

[krystofwoldrich]

Description

The goal of this task is to add support for the new manual APIs in Sentry Expo Plugin.

• Initially as opt-in. useNativeInit: true
• The plugin should warn users if native init is already present in the native code.
• The plugin should patch AppDelegate.mm for iOS and MainApplication.kt for Android.

[renchap]

Are you planning for this to be in 7.0? This would be a very nice improvement for Expo users, and the work seems to be nearly finished?