Update CodePush guide to use DebugIDs

[krystofwoldrich]

Description

https://docs.sentry.io/platforms/react-native/manual-setup/codepush/

The current CodePush guide still explains importance of release name and dist for source maps.

RN now supports Debug IDs which will simplify the guide and the conditional init can be removed.

The current guide works, but it's necessary complex and out of sync when compared to the rest of our source maps guides.

https://docs.sentry.io/platforms/react-native/sourcemaps/uploading/

The CodePush guide should be moved under uploading source maps.