Bump react-native to 0.63.x

[alexsegura]

This would allow to support dark mode

Needs #722

[alexsegura]

There is a problem with React Native 0.63.x → the app can't be bundled for release on iOS.

The following error occurs:

File [...]/CoopCycle.app/main.jsbundle does not exist. 
This must be a bug with React Native, please report it here: https://github.com/facebook/react-native/issues

The actual problem is that, during the Bundle React Native Code And Images build phase, the script to generate the bundle triggers a syntax error:

There are some people reporting the same problem

• 0.63 upgrade results in a bundle that never finishes building facebook/react-native#29351
• [RN v0.63.2] Fix Xcode bundler in staging and release facebook/react-native#29477
• babel-plugin-module-resolver doesn't work with react-native 0.63.0+ for iOS production builds facebook/react-native#29636
• change ../node_modules/react-native/packager/react-native-xcode.sh facebook/react-native#29818

[alexsegura]

The master branch has been reverted to use React Native 0.62

The changes made for 0.63 have been backed up in the bump-rn-63 branch

[alexsegura]

Actually dark mode was fixed here

[alexsegura]

Version 0.63.3 is out, and it seems to fix the issue