Support multiple bundles on react-native using repack

[oblador]

We are moving to use repack to bundle our React Native app to support bundle splitting. However the current sentry integration assumes a single bundle, so it will only upload the main one.

[jennmueng]

@oblador I'm not too familiar with repack, but from the looks of it we would either need a repack-specific build script that detects the various bundles or if it outputs the output to a folder upload the whole contents of that folder. For now you should be able to instead upload each bundle generated by repack individually with the sentry-cli.