Summary:
This makes a few change to the template xcodeproj
- Update to recommended settings for Xcode 12
- Remove the main.jsbundle file that doesn't exists, this file is included automatically in the app bundle and doesn't need to be in xcode (it won't even be at that path).
- Add -e to the bundle images script. It seems like Xcode doesn't fail the build on script errors anymore so this makes it so the build stop. If it doesn't stop the app will launch and crash because the bundle doesn't exist (note this is only if running the app in release mode since in debug we don't generate the bundle).
## Changelog
[iOS] [Added] - Update template to xcode 12
Pull Request resolved: https://github.com/facebook/react-native/pull/30150
Test Plan: Made the same changes in an app and made sure it ran well.
Reviewed By: cpojer
Differential Revision: D24237481
Pulled By: sammy-SC
fbshipit-source-id: 2b06a24c510c423eb45a1a840ea365b64506321b
6685aba462